will be using -> will use

-> thì TLĐ : s + will + V nguyên mẫu

2 theirs -> their

-> ttsh + N

3 her -> hers

II

1 i  used to stay up late to watch football matches last year but now i don't

-> used to + V nguyên mẫu

2 i haven't visted my native village since i was ten

-> thì HTHT + since : s + have / has + VPII + since + 1 mốc thời gian

-> since + thì QKĐ

3 developed countries have less population problems than developing countries

-> so sánh hơn của  litlle -> less

4 in spite of the bad weather i had a very good time in Brazil

bổ sung :

how many people are there in HCM city

$28.$ B

- Vế trước "I think" → Ý kiến cá nhân nên dùng thì tương lai đơn: S + will + V.

- Sửa: will be using → will use.

$29.$ D

- Trước danh từ: Tính từ sở hữu, đại từ sở hữu không đi kèm với danh từ.

- Sửa: theirs →their.

$30.$ C

- Tính từ sở hữu theo sau là danh từ, do đó câu này sai.

- Sửa: her → hers.

$31.$ I used to stay up late to watch football matches last year.

- "used to + V": hành động từng làm nhưng giờ thì không.

$32.$ I haven't visited my native village since I was ten.

- S + last + V (-ed/ bất quy tắc) + when + time = S + haven't/ hasn't + V3 + time.

$33.$ Developed countries have less population than developing countries.

- Nhiều hơn >< Ít hơn.

→ more >< less.

$34.$ How many people are there in Ho Chi Minh City?

$35.$ In spite of the bad weather, I had a very good time in Brazil.

- In spite of + Noun/ Noun phrase/ V-ing, S + clause.