II. Dùng giới từ:

3. about (lo lắng cho)

4. for (tốt cho)

5. of (sợ hãi)

6. at (nhìn vào)

III. Dùng liên từ because:

1. c. I was absent from class yesterday because I was sick. (Tôi nghỉ học vì tôi bị ốm)

2. e. Minh is going to see the dentist because he has a toothache. (Minh đến gặp nha sĩ vì bị sâu răng)

3. f. She has healthy teeth because she brushes her teeth after meals. (Cô ấy có răng khỏe mạnh vì cô đánh răng sau khi ăn)

4. b. Children have toothache because they eat a lot of candy. (Trẻ con bị sâu răng vì chúng ăn nhiều kẹo)

5. a. He was happy because his decaying tooth stopped hurting. (Anh ấy vui vì cái răng thối đã ngưng đau nhức)

6. d. We jog every morning because it's good for our health. (Chúng tôi đi bộ mỗi sáng vì nó tốt cho sức khỏe)

IV. Hỏi Why trả lời Because:

1. Why was he scared? Because he hated the sound of the drill. 

2. Why do children often have toothache? Because they eat lots of candy.

3. Why were you late for class yesterday? Because I missed the first bus.

4. Why did her tooth hurt? Because she had a cavity.

Why + do/does/did + sb + bare-inf?

Why + was/were + sb + adj + ... ?

Because + S + V