1. The mails are opened by the secretary every morning.

2. John asked how long it took Mary to get to London.

3. If she had a college degree, she could be employed.

4. Because of the heavy rain, I couldn't go to school on time.

5. You are too young to have a front - door key.

6. She's the journalist whose article was on the front page of The Times.

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1. It is important for her to see a doctor now.

2. The house which was painted green belongs to Mrr. Pike.

Part 1:

1. The mails are opened by the secretary every morning. 

Ở đây mình thấy the mails từ object 2 của câu trên lại thành chủ ngữ của câu cần điền => Bị động.

2. John asked Mary how long it took her to get to London.

Này là câu dạng reported speech bình thường thôi ạ.

3. If she had a college degree, she could be employed.

Ở đây là dạng các câu điều kiện, ở trên là đk loại 1 thì ở dưới chỉ là giả đinh thôi, nên là loại 2 ;-;

4. Because of the heavy rain, I couldn't go to school on time.

Because of + noun, ta đổi "the rain was so heavy" ra thành danh từ => the heavy rain.

5. You are too young to have a front-door key. 

Câu trên dùng so - that thì câu dưới có too-to. Mình được dạy sương sương thế (tùy trường hợp)

6. She's the journalist whose article was on the front page of The Times.

Đây là bài dạng mệnh đề quan hệ

Part 2:

1. It is important for her to see a doctor now.

2. The house, which is painted green, belongs to Mr. Pike.