Question

Answer 1

6 He can make people understand him when he speaks English

7 She doesn't study hard enough

8 The car is too expensive for us to buy

Answer 2

6. He can make people understand him when he speaks English.
7. She doesn't study hard enough.
8. The car is so expensive that we can't buy it.

Answer 3

He can make people understand when he speaks English.

 she doesn't study hard enough 

this car is too expensive for us to buy