I.
1/ A
2/ A
3/ C
4/ C
5/ C
II.
6/ A 14/ C
7/ C 15/ C
8/ C 16/ B
9/ A 17/ D
10/ A 18/ B
11/ D 19/ B
12/ C 20/ D
13/ D 21/ D
22/ B
III.
23/ D
24/ B
25/ B
IV.
1/ The picture at which she was looking is beautiful.
2/ I enjoyed the music which we listened to after dinner.
3/ I met the people about whom you told me.
4/ The market to which I usually go has refresh vegetables.
5/ I couldn't understand the woman to whom I talked on the phone.
6/ John whom I've known for a very long time, is one of my closest friend.
7/ The population of London, which was once the largest city in the world, is now falling.
V.
1/ A
2/ B
3/ D
4/ C
5/ A
VI.
1/ B (natural-> national)
2/ B ( bỏ that)
3/ C (whom-> who)
4/ C (was-> were)
5/ A (are-> is)
