33. Nien wasn't old enough to be in our class

- S tobe not adj enough to V

34. She looked happy because she passed the test

- because : bởi vì

35. He is tall enough to play volleyball

- S tobe adj enough to V

36. I used to play marbles when I was young

- used to V

`33.` Nien wasn't old enough to be in our class

`\text{enough: S + be(not) + adj + enoough + to Vinf...}`

`34.` She looked happy because she passed the test

`\text{Because: mệnh đề chỉ kết quả + because + mệnh đề chỉ nguyên nhân}`

`35.` He is tall enough to play volleyball

`\text{enough: S + be(not) + adj + enoough + to Vinf...}`

`36.` I used to play marbles when I was young.

`\text{Used to: S + used + to Vinf + (O) +....}`