I.

1. B -> teaching

2. A -> exciting

3. B -> how

4. C -> most

5. B -> for

II.

1. My brother is interested in listening to music.

2. Someone finds climbing the mountain alone very challenging.

3. I have never watched "Iron man" before.

4. Ann thinks arranging flowers is much more interesting than bird-watching.

5. Phong has collected old coins for 5 years.

6. Vinh began to play the guitar 3 years ago.

7. Apple aren't usually as expensive as mangoes

8. My father used to smoke 3 years ago.

9. Although he was ill, he managed to go to the church.

10. In spite of being hungry, he didn't eat much.

Ex 1.

1,B-taching

2,A-exciting

3,B-how

4,C-most

5,B-for

Ex2

1, ... in listening to music.

2, ...that i is very challanging to climb the mountain alone

3,... ever watched 'Iron man" before.

4,...that bird watching is not as interesting as arranging flower.

5,... been collected old coins for 5 years.

6,... to play the guitar 3 years ago.

7,... are not usually as expensive as mangoes.

8,... to smoke 3 years ago.

9,... he was ill,.....

10,....the facts that he was hungry,he didn' eat much.