2．Scientists have advanced many theories about why human beings cry tears，none of which has been proved.(2016·浙江)

3．Some experts think reading is the fundamental skill upon which school education depends.(2015·安徽)

4．He wrote many children's books，nearly half of which were published in the 1990s.

(2015·重庆)

5．Creating an atmosphere in which employees feel part of a team is a big challenge.(2015·浙江)

6．September 30 is the day by which you must pay your bill.(2014·大纲全国)

Ⅱ.单句改错(每小题仅有1处错误)

1．There，Katia will introduce me to some of her friends，one of has been to China several times.(2011·重庆，短文改错)

2．It is also a window ∧through which we can learn about American society.(2008·重庆，短文改错)

Ⅰ.单句语法填空

1．Is this the girl to whom you lent your bike?

2．This is the pen with which I wrote the letter.

3．He is just the student with whom I want to make friends.

4．Water is important，without which people can not live.

5．He is the student from whom I borrowed this dictionary.

Ⅱ.单句改错(每小题仅有1处错误)

6．I have a new book，the cover of is very nice.

7．The girl has a few friends，one of is a lawyer.