3. Making crafts or collecting things like stamps and coins are very interesting. (It’s)

It’s very interesting to make crafts or collect things like stamps and coins

4. We usually visit museums when we have leisure time. (enjoy)

we enjoy visiting museums when we have leisure time.

5. I don’t like to get up early and prepare breakfast in the cold winter days. (hate)

i hate getting up early and preparing breakfast in the cold winter days.

6. Hung drives more carefully than his brother. (carefully)

Hung's brother drivers carryfully than he does drives as carefully as he does / drivers carryfully than he 

7. Going by taxi is faster than going by bus but it costs more than a bus. (less)

Going by a bus is slower than going by a taxi but it costs less than a taxi.

8. Mr. Quynh is the happiest person in the village.

   No one in the village is happier than Mr. Quynh.