Đáp án : 

Bài 6 : 

1. + They were not here so they could not help you 

    + They could not help you because they were not here 

2. + It's raining so i can't go out now 

    + I can't go out now because it's raining 

3. + We haven't got any food so we are going shopping 

   + We are going shopping because we haven't got any food 

4. + There was fog so their flight was delayed 

    + Their flight was delayed because there was fog 

5. + The film was boring so we decided to go home 

    + We decided to go home because the film was boring 

6. + I couldn't do this exercise so i asked Tom for help 

    + I asked Tom for help because i couldn't do this exercise 

Bài 7 : 

1. The holidays were so cheap that they booked one immediately

2. Mr. Smith is such a strong man that he can lift up a heavy box easily

6)

1:  They weren't here so they could not help you.

     They couldn't help you because they were not here.

2:  It's raining so i can't go out now.

     I can't go out now because it's raining.

3:  We haven't got any food so we are going shopping.

     We are going shopping because we haven't got any food.

4: There was fog so their flight was delay.

    Their flight was delayed because there was fog.

5: The film was boring so we decided to go home.

    We decided to go home because the film was boring.

6: I couldn't do this exercise so I asked Tom for help.

    I asked Tom for help because I couldn't do this exercise.

7)

1: The holidays were so cheap that they booked one immediately.

2: Mr. Smith is a strong man that he can lift up a heavy box easily.