[填空题]Why is ocean exploration not so expensive as space travel Because ______ for submersibles to get away from the Earth’s gravity.

[填空题]Why is ocean exploration not so expensive as space travel
Because ______ for submersibles to get away from the Earth’s gravity.

[单项选择]What is the reason why so many people are ill

[单项选择]第三篇Why So Many Children In many of the developing countries in Africa and Asia, the population is growing fast. The reason for this is simple: Women in these countries have a high birth rate — from 3.0 to 7.0 children per woman. The majority of these women are poor, without the food or resources to care for their families. Why do they have many so children Why don’t they limit the size of their families The answer may be that they often have no choice. There are several reasons for this. One reason is economic. In a traditional agricultural economy, large families are helpful. Having more children means having more workers in the fields and someone to take care of the parents in old age. In an industrial economy, the situation is different. Many children do not help a family; instead, they are an expense. Thus, industrialization has generally brought down the birth rate. This was the case in Italy, which was industrialized quite recently and rapidly. In the early part of the twenti
A. may limit income.
B. isn’t necessary.
C. can be an advantage.
D. is expensive.

[单项选择]We don’t know why so many people in that region like to wear dresses of such（）colors.
A. low
B. humble
C. mild
D. dull

[单项选择]Why is the man so annoyed
A. Because he didn’t like listening to radio.
B. Because his sister made him study very hard.
C. Because the noise disturbed him so much.