III/1. don't study

2. to turn

3. washing

4. has written

5. working

IV/1. It is necessary that we go home now.

2. Why don't you turn on the light in your room?

3. Yesterday they suggested that she stay with her uncle on holiday.

4. He turns of the gas after he finishes cooking.

5. Would you mind lending me your motorbike until this weekend?

6. We all look forward to making a trip to next town.

I

1 don't

2 to turn

3 washing ( tobe used to + Ving)

4 has written

5 working ( enjoy+ Ving )

II

1 It is necessary for us to go home now.

2 Why don't you turn off the light before leaving room?

3 Yesterday they suggested that she should stay with her uncle on holiday.

4. He turned off the gas after he had finished cooking.

5. Would you mind lending your motorbike until this weekend?

6. We are all look forward to making a trip to the next town.