问题 单项选择题

下面对for循环初始化部分的描述中,正确的是( )。

A.首先执行初始化操作

B.必须执行初始化操作

C.先执行循环体内容再执行初始化操作

D.以上答案都不正确

答案

参考答案:A

解析: for循环执行时,首先执行初始化操作,然后判断终止条件是否满足,如果满足,则执行循环体中的语句,最后执行迭代部分。

阅读理解

Using too much water or throwing rubbish into our rivers are clear ways that humans can put our water supply in danger , but we also affect our water supply in less obvious ways. You may wonder how paving(铺砌) a road can lead to less useable fresh water. A major part of the water we use every day is groundwater. Groundwater does not come from lakes or rivers. It comes from underground. The more roads and parking lots we pave the less water can flow into the ground to become groundwater.

Human activity is not responsible for all water shortages(短缺). Drier climates are of course more likely to have droughts(干旱) than areas with more rainfall, but in any case, good management can help to make sure there is enough water to meet our basic needs.

Thinking about the way we use water every day can make a big difference, too In the United States , a family of four can use 1. 5 tons of water a day! This shows how much we depend on water to live, but there’s a lot we can do to lower the number.

You can take steps to save water in your home. To start with use the same glass for your drinking water all day. Wash it only once a day. Run your dishwasher (洗碗机)only when it is full 。Help your parents fix any leaks in your home. You can even help to keep our water supply clean by recycling batteries instead of throwing them away.

小题1:Which of the following is most likely to lead to less groundwater?

A.Using river water.

B.Throwing batteries away.

C.Paving parking lots.

D.Throwing rubbish into lakes.小题2:What can be inferred from the text?

A.All water shortages are due to human behavior.

B.It takes a lot of effort to meet our water needs.

C.There is much we can do to reduce family size.

D.The average family in America makes proper use of water.小题3:The last paragraph is intended to             .

A.show us how to fix leaks at home

B.tell us how to run a dishwasher

C.prove what drinking glass is best for us

D.suggest what we do to save water at home小题4:The text is mainly about          .

A.Why paving roads reduces our water

B.how much we depend on water to live

C.why droughts occur more in dry climates

D.how human activity affects our water supply

单项选择题