用that不用which的情況：
1.先行詞是不定代詞或被不定代詞修飾，如much, little, none, all, few, everthing, anything.等
例句：
Is there anything that I can do for you.
(這裡有什麼，我可以為你做的事嗎？)
The boy has little money that he got from his boss.
(這個男孩從他老闆那裡得到了一點錢)
2.當先行詞是序數詞或最高級修飾時，或者先行詞就是序數詞或最高級時。
例句：
The first thing that I should do is to review my lessons.(第一件我需要做的事就是複習我的課程。)
The Old man and Sea is the most interesting
book that I have read.(老人與海是我讀過最有趣的書。)
3. 當先行詞有the very, the same, the only,vthe last 修飾時。
例句：
This is the only thing that I can do now.
4.當先行詞以who, 或which開頭時。
例句：
Which is the pen that you lost.
(哪一個是你丟的筆？)
5.先行詞同時包含人或物時。
They talked about the teachers and the schools that they know.
(他們討論著他們所知道的學校和老師。)
只用which的情況：
1.先行詞本身就是that時。
例句：
What's that which flashed in the sky just now.
(那是什麼，剛剛在天空一閃而過。)
2.關係代詞前有介詞且指物時。
例句：
The house in which I used to live has become a clothes shop.
(我曾經住的那個房子現在變成了一個衣服商店。)
上次知識回顧：
that:先行詞是人/物;可在從句中做主語/賓語。
例句:
1.She is the girl that I called three times
yesterday.(她就是那我昨天叫了三遍的女孩。)
分析: 先行詞是girl(人); that 在從句中充當called的賓語。
2.This is the girl that called me three times
yesterday.(這就是那個叫我三遍的)
分析: 先行詞是girl(物); that在從句中充當主語
which：先行詞是物;可在從句中作主語，賓語。
例句：
1.This is the book that my father bought for
me. (這就是我爸爸給我買的書。)
分析：先行詞是book; that 在從句中作賓語。
牛刀小試:
1.This is one of the best films _______.
A. that have been shown this year
B. that have shown
C. that has been shown this year
2.Is there anyone in your class ______family is in the country?
A. who B. who's C. whose
3. I want to use the dictionary ______was used yesterday.
A. which B. who C. what
4. He talked a lot about things and persons ________they remembered in the school.
A. which B. that C. whom
5. In our factory there are 2,000 workers, two thirds of ____are women.
A. them B. which C. whom
6. The man ______hair is white is American.
A. which B. whose C. what
7.Do you know the woman about her information _____ is crying over there?
A. who B. whose C. which