4．
1 Nobody knows who will be e as president or vice president of this country.
2 According to the constitution, it is compulsory for a citizen to ______________(承担) military service.
3 People who can’t ________________(辨别) between colors are said to be color-blind.
4 —Why are you late?
—I was about to arrive when it o to me that I had left my bag home, so I had to fetch it.
5 But at last the determination and patience of the scientists ___________ __________(得到好结果，回报) in1996 with a breakthrough—the cloning of Dolly the sheep.
6 I ___________ ___________(开始，着手) researching the habits of snakes to find the easiest way to trap them.
7 I found my bike ___________ ___________ ___________(借助于) a notice in the newspaper.
8 All attempts to rescue the boy with cancer were _____________ _____________(无效果的，无用的)
9 We ___________ __________ ___________(与……合作或一起) a couple from my hotel(Peter and Terri) and hired a car.
10 In many aspects natural clones, such as identical twins, do not ____________(不同，相异) greatly from man-made ones.