1. who/ which vs that
歧义句. *Correct the sentences below which contain grammatical mistakes
S1. Correct the sentences below, which contain grammatical mistakes. （which 用于增加额外信息,下面的句子都是有语法错误的）
S2. Correct the sentences below that contain grammatical mistakes.（that 用于限定前面的sentences，只修正有语法错误的句子）
更清楚的表达：
S3. Correct the sentences below, all of which contain grammatical mistakes.
S4. Correct only those sentences below that contain grammatical mistakes.
who和that
S5. My sister, who lives in Paris , is a researcher. (who用于补充)
S6. My sister that lives in Paris is a researcher.（that用于限定）
错误句子： * This is followed by a characterization of the states poorly represented at atmospheric pressure.
Note: In spoken English, people do not usually make such a distinction and may simply use which for things, and who for people, irrespectively of whether they are using defining or non defining clauses.
***Which, that和who只能指它们前面的名词。
2. -ing form vs. that
ing有的时候可以和从句互换，这是两个没用歧义的句子
S1. Those students wishing to participate in the call for papers should contact …
S2. The professor giving the keynote speech at the conference is from Togo.
歧义句. * Professor Rossi teaches the students having a good level of English. （谁英语水平好？）
3. - ing form vs. subject + verb
如果使用的是主动语态最好是加上主语。
歧义句： * If you take your young daughter in the car, don’t let her put her head out of the window while driving.
歧义句： * After consuming twenty bottles of wine, the conference chair presented the awards to the fifty best PhD students.
S3. If you take your young daughter in the car, don’t let her put her head out of the window while you are driving.
S4. After the fifty best PhD students had consumed twenty bottles of wine, the conference chair presented them with the awards.
4. - ing form with by and thus
歧义句 * This will improve performance keeping clients satisfied.
S1. This will improve performance thus keeping clients satisfied.
S2. This will improve performance by keeping clients satisfied.
添加额外信息时，可以直接用and
歧义句. * This section focuses on the reasons for selecting these parameters, trying to explain the background to these choices.
S3 This document focuses on the reasons for selecting these parameters, and tries to explain the background to these choices.
