Thanks to scientific research, we now have a good understanding of ______ an earthquake is and why it happens.

--- How easy is it to find a taxi in this city?
---Simply _______ your hand, and a taxi appears in no time.

---Would you please help me get this job with the company?
---Sure. You know, I would do ______ for you.

_______ is no doubt that the world is being smaller, due to the technological advances made by the computer.

You will never guess ______ when she found herself ranked first in the competition.

You didn't let me drive. If we     in turn, you      so tired.

I won’t change my belief _________ success comes to those who act．

---_______ one and a half months enough for the project to be finished?
　　---I am afraid not. The professor is ill and only after he recovers ________ go on with it.

---What did Kincaid say just now?
　　---He said he ________ a dog if he hadn’t been away from home too much.

--Whenever I come to visit, he is always watching TV.
--You’re really observant. He can’t help but ________ some TV during meals or before bed.