Chào mừng bạn đến với HelloChao

1. When I came, they were still working in the garden

2. She is good at English

3. Phone me as soon as he'll come back

4. I saw this boy open the door of the car

5. One of the books is on agriculture

6. If she hadn't had a good knowledge of E, Carmen wouldn't have been accepted by the travel bureau

Telephone me as soon as he comes back

I saw this boy opening the door of the car (see him at that time, not whole time)

One of the books is about agriculture.
4. I saw this boy open/opening ...... Both ways are correct in this case, we dont have the whole paragraph to imagine what context it it.
3. Both phone and telephone are ok .
 

1. When I came, they were working in the garden.

2. She is good at English.

3. Please, call me as soon as he comes back.

4. I saw the boy who opened the car door. (not sure)

5. One of the books is on agriculture.

6. If Carmen doesn't have a good knowledge of English, she won't be accepted by the travel bureau.

Câu này chỉ dùng loại 1 thôi. Bởi vì nó diễn tả một sự kiện có nguyên nhân và hệ quả, đúng với quy luật logic của vấn đề.

@Huỳnh Bá Học : you was wrong man :). Take my comment above as the reference.

Furthermore, your sixth answer and the following explanation are not correct. I'll be back with more comprehensive explications.  

4. I saw the boy who opening the car door.

There is no problem with the sixth answer. I'm not convinced by Zaccheus. Please tell me what is the basic for you to say so, Zaccheus?

Mình không nghỉ cách làm của bạn Huỳnh Bá Học là đúng. Đề ra là câu điều kiện loại 3 rõ ràng còn gì.