1. Jane is the only person to know the secret.

2. Sheila couldn’t come to the party, which was a pity.

-> 2 câu trên đầu là dạng mệnh đề quan hệ

3. Do you have any trouble working out this problem ?

-> trouble + Ving

4. I didn’t work hard. I really regret disappointing my parents.

->regret + Ving : quên cái gì dùng trong QK

5. It has rained cats and dogs for the past few days.

-> có for ta dùng thì HTHT

6. Jane was mopping the floor when she slipped and fell 

-> hành động đạng xảy ra thì có hành động khác xen vào

8.This time tomorrow, we will be doing our English test.

-> có this time tomorrow dùng thì TLTD