Scientists will have to come_______ new methods of increasing the world’s food supply.

It was ________ impossible for her to catch the 9 o’clock train. I know she got up at 9:15．

Since David ______ downloaded a virus into his computer, he can not open the file now.

---Mary has been trained hard for the last two years.
---______ she did so well at the track and field meet yesterday.

–Have you got ready for your studying plan?
--Yes! I have made it ______. Please give me some suggestions and then I will make some changes.

But as the moon gave ________ light, she didn’t dare open a window.

--- What a lot of fun it is to play on a frozen sports field!
--- Isn’t it rather risky,       ?

We decided not to climb the mountains as it was raining ________ .

As a student in Senior Three, I must work hard． ___________, I should take exercise to strengthen my body．

The bank refused to give the company more time, and ________, it broke down.