一.本课要点及示例

在这一课里, 我们学习用 "如果" if, i-f, if 和过去完成时态作句子来表示跟过去 事实相反的条件和结果.比方,"当时我要是看见了你,我一定会跟你打招呼的." 这句话英文应该这样说: If I had seen you. I certainly would have said hello to you. (来源：EnglishCN.com)

下面我们念一段对话, 多举几个例子给你听.这段对话的内容是说凯特跟同事 比尔谈起了他们小时候上历史课的事情. 请你注意听两位英文老师的发音和 语调.

M: When did you decide to be a school teacher,Kate?

F: When I was in grade school, I had a teacher who I liked very much. I wanted to be like she was.

M: What made her so special?

F: She used to make things interesting and exciting to learn.

M: Like what?

F: If you had heard her history lessons, you would have thought that history was fascinating.

M: If you had been in our history class, you would have found history very boring. Our teacher just taught names and dates.

F: If I had been in your class, maybe I would have become something besides a teacher.

M: If I had been in your class, maybe I would have become a history teacher instead of a gym teacher.

现在我们把对话再念一遍给你听. 这次老师念得比较慢, 请你注意听.

M: When did you decide to be a school teacher,Kate?

F: When I was in grade school, I had a teacher who I liked very much. I wanted to be like she was.

M: What made her so special?

F: She used to make things interesting and exciting to learn.

M: Like what?

F: If you had heard her history lessons, you would have thought that history was fascinating.

M: If you had been in our history class, you would have found history very boring. Our teacher just taught names and dates.

F: If I had been in your class, maybe I would have become something besides a teacher.

M: If I had been in your class, maybe I would have become a history teacher instead of a gym teacher.

下面两位老师把对话里包含了今天要学的语法的句子挑出来,再念一遍给你听.

F: If you had heard her history lessons, you would have thought that history was fascinating.

M: If you had been in our history class, you would have found history very boring.

F: If I had been in your class, maybe I would have become something besides a teacher.

M: If I had been in your class, maybe I would have become a history teacher.

二.用 IF 引导跟过去事实相反的情况

听了上面那些句子, 我想你已经注意到怎么样用过去完成时态作句子来表达 跟过去事实相反的情况. 现在我们开始作练习, 多学学这种说法. 第一组练习 的作法是比尔用过去时态说明发生在过去的事情. 凯特就用过去完成时态作 假设性句子, 说明如果比尔过去那么作了, 他可能会有什么结果. 下面就是一 个例子:

M: I wasn't in your class. I didn't become a history teacher.

F: If you had been in my class,maybe you would have become a history teacher.

现在请你一边听句子的意思, 一边注意语法的变化.

M: I wasn't in your class. I didn't become a history teacher.

F: If you had been in my class, maybe you would have become a history teacher.

M: I wasn't in your class. I didn't think that history was fascinating.

F: If you had been in my class, maybe you would have thought that history was fascinating.

M: I wasn't in your class. I didn't think that history was exciting.

F: If you had been in my class, maybe you would have thought that history was exciting.

下面改由凯特念过去时态句子;比尔念的是假设性句子.还是请你注意听.

F: I wasn't in your class. I didn't become a gym teacher.

M: If you had been in my class, maybe you would have become a gym teacher.

F: I wasn't in your class. I didn't think that history was boring.

M: If you had been in my class, maybe you would have thought that history was boring.

F: I wasn't in your class. I didn't think that history was just names and dates.

M: If you had been in my class, maybe you would have thought that history was just names and dates.

在刚才那组练习里我们用 "也许" maybe 加上 would 再加上完成时态作了一 些假设性句子, 这种说法也可以改用 might 加上完成时态来表达. 比方:

Maybe he would have become a history teacher. 可以改为 He might have become a history teacher. 下面我们作一组练习把这两种说法作个比较.首先 请你注意听老师用第一种说法说一句话,然后请你跟学生一起改用代名词跟 第二种说法把那句话表达出来.下面就是一个例子:

M: If Bill had been in Kate's class, maybe he would have become a history teacher.

F: If he had been in her class, he might have become a history teacher.

现在我们开始作练习.

M: If Bill had been in Kate's class, maybe he would have become a history teacher.

F: If he had been in her class, he might have become a history teacher.

M: If Bill had been in Kate's class, maybe he would have thought that history was fascinating.

F: If he had been in her class, he might have thought that history was fascinating.

M: If Bill had been in Kate's class, maybe he would have thought that history was exciting.

F: If he had been in her class, he might have thought that history was exciting.

M: If Kate had been in Bill's class, maybe she would have become a gym teacher.

F: If she had been in his class, she might have become a gym teacher.

M: If Kate had been in Bill's class, maybe she would have thought that history was boring.

F: If she had been in his class, she might have thought that history was boring.

M: If Kate had been in Bill's class, maybe she would have thought that history was just names and dates.

F: If she had been in his class, she might have thought that history was just names and dates.

下面我们用美国历史作例子, 学学跟过去事实相反的说法. 练习的作法是老 师用过去时态说出美国历史上的一项事实,比方"移民来到美洲; 殖 民地因此 成立." The immigrants came to America. The colonies were established. 学生 就把句子改成:"如果移民没有到美洲, 殖民地就不会成立." If the immigrants hadn't come to America, the colonies wouldn't have been established. 在这组练 习里有些新词汇,比方 "压迫" oppress, "革命" revolution,"打败" defeat,"奴隶" slave 等等. 请你注意听. 学生作句子的时候请你也一起作.

M: The immigrants came to America. The colonies were established.

F: If the immigrants hadn't come to America, the colonies wouldn't have been established.

M: The taxes were raised.The colonists were unhappy.

F: If the taxes hadn't been raised, the colonists wouldn't have been unhappy.

M: The colonists were oppressed. There was a revolution.

F: If the colonists hadn't been oppressed, there wouldn't have been a revolution.

M: The colonists fought the revolution against the British. They gained independence.

F: If the colonists hadn't fought the revolution against the British, they wouldn't have gained independence.

M: The colonists gained independence. The U.S. became a country.

F: If the colonists hadn't gained independence, the U.S. wouldn't have become a country.

M: France needed money. It sold a piece of land to the U.S.

F: If France hadn't needed money, it wouldn't have sold a piece of land to the U.S.

M: The U.S. bought that piece of land. The size of the U.S. doubled.

F: If the U.S. hadn't bought that piece of land, the size of the U.S. wouldn't have doubled.

M: People of Texas fought a war against Mexico. They became independent.

F: If people of Texas hadn't fought a war against Mexico, they wouldn't have become independent.

M: Texas became independent. It joined the U.S.

F: If Texas hadn't become independent, it wouldn't have joined the U.S.

M: The U.S. defeated Mexico. California and New Mexico became part of the U.S.

F: If the U.S. hadn't defeated Mexico, California and New Mexico wouldn't have become part of the U.S.

M: The North won the Civil War. Slaves were freed.

F: If the North hadn't won the Civil War, slaves wouldn't have been freed.

M: Russia sold Alaska to the U.S. It became an American state.

F: If Russia hadn't sold Alaska to the U.S., it wouldn't have become an American state.

现在我们再来练习怎么表达跟过去事实相反的条件和结果.下面我们还是请 老师用过去时态说出美国历史上的一些事迹, 比方 "英国宣称北美洲部分土 地属于他们. 因此加拿大没有变成美国的一部分." England claimed part of North America.Canada didn't become part of the U.S. 请你用 might 把句子改成 "如果英国没有宣称北美洲部分土地属于他们, 加拿大就可能变成美国的一 部分." If England hadn't claimed part of North America, Canada might have become part of the U.S.这组练习里也有一些有用的词汇, 比方 "解决" settle, "歧见" difference, "妥协" compromise, "反对" oppose. "避免" prevent 等等,请 你在作练习的时候特别注意听. 你每作完一句老师就会念正确答案给你听.

现在我们开始.

M: England claimed part of North America. Canada didn't become part of the U.S.

F: If England hadn't claimed part of North America, Canada might have become part of the U.S.

M: England and the U.S. settled their differences.They didn't go to war.

F: If England and the U.S. hadn't settled their differences, they might have gone to war.

M: England and the U.S. compromised. They didn't fight against each other.

F: If England and the U.S. hadn't compromised, they might have fought against each other.

M: The South opposed President Lincoln's policy. The Civil War couldn't be prevented.

F: If the South hadn't opposed President Lincoln's policy, the Civil War might have been prevented.

M: The South was defeated. The U.S. didn't become two countries.

F: If the South hadn't been defeated, the U.S. might have become two countries.

三.听短文回答问题

今天我们要听的文章简单谈到美国建国的经过; 文章里许多词汇和句子都是 我们刚才练习过的.

现在请你注意听. 等一会我们要根据文章内容问你几个问题.

Compared to the history of China, the history of the United States is quite short. It began little more than 200 years ago. In 1776, 13 colonies located on the eastern coast of North America declared independence and fought a revolution against the British. In 1783 the colonists won the revolution and gained their independence.

After the revolution, the United States bought a large section of country from Napoleon of France. This purchase doubled the size of the United States. Napoleon needed money for his European wars. If he hadn't needed that money, the United States might have stayed a small country. Texas and most of what is now the southwestern part of the United States belonged to Mexico. The people of Texas fought a revolution against Mexico.

They became independent and joined the United States. Later, the United States and Mexico went to war. If Mexico had defeated the United States, in that war, California and New Mexico would have been part of Mexico today.

The British and the Americans both claimed the northwestern part of the country. They settled their differences with a compromise. South of the 49th parallel was the United States.

North of the 49th parallel was Canada which was controlled by England.

In 1861 one-half of the United States did go to war with the other half. This was the Civil War.

President Lincoln wanted to free slaves. He was supported by the North but opposed by the South. The South wanted to separate from the rest of the country and become independent. After 4 years of war, the South was defeated.

Following the Civil War, the United States bought Alaska from Russia. At that time many people didn't think Alaska was important, but today it is the largest state in the country and a very important one too.

现在请你回答下面三个问题. 你回答之后, 老师会念出正确答案给你听, 让你 作个比较, 看你答对了没有.

第一个问题是:

M: How did the United States become a country?

F: Colonists defeated the British in a revolution.

第二个问题是:

M: Which countries have sold land to the U.S.?

F: France and Russia have sold land to the U.S.

第三个问题是:

M: What was the outcome of the U.S.-Mexican War?

F: Mexico was defeated. California and New Mexico became part of the U.S.