问题 选择题

在抗洪抢险中,战士驾驶摩托艇救人。假设江岸是平直的,洪水沿江向下游流去,水流速度为v1,摩托艇在静水中的航速为v2。战士救人的地点A离岸边最近处O的距离为d。若战士要在最短时间内将人送上岸,则摩托艇登陆的地点离O点的距离为

A.

B.

C.

D.0

答案

答案:B

题目分析:摩托艇要想用最短的时间过河,则船头方向应该指向正对岸,此时过河的时间为,被河水冲下的距离为=,选项B正确。

阅读理解

When you want to go shopping, decide how much money you can spend on new clothes. Think about the kind of clothes you really need. Then look for those clothes you really need. Then look for those clothes on sale.

There are labels(标签) inside all new clothes. The labels tell you how to take care of your clothes. The label for a shirt may tell you to wash it in warm water. A sweater label may tell you to wash in cold water. The label on a coat may say “dry clean only”, for washing may ruin this coat. If you do as the directions (说明)on the label, you can keep your clothes looking their best for a long time.

Many clothes today must be dry cleaned. Dry cleaning is expensive. When buying new clothes, check to see if they will need to be dry cleaned. You will save money if you buy clothes that can be washed.

You can save money if you buy clothes that are well made. Well-made clothes last longer. They look good even after they have been washed many times. Clothes that cost more money are not necessarily(不一定) better made. They do not always fit better. Sometimes less expensive clothes look and fit better than more expensive clothes.

小题1:If you want to save money, you had better buy clothes that __ .

A.don’t fit you

B.don’t last long

C.need to be dry cleaned

D.can be washed小题2:The labels inside the clothes tell you______.

A.how to keep them looking their best

B.how to save money

C.whether they fit you or not

D.where to get them dry cleaned小题3:The first thing for you to do before you buy clothes is __ .

A.to look for well-made clothes

B.to see how much money you can spend on it

C.to know how to wash them

D.to read the labels inside them小题4:We learn from the passage that cheaper clothes __ .

A.are always worse made

B.must be dry cleaned

C.can not be washed

D.can sometimes fit you better小题5:The best title for the passage should be __ .

A.Buy Less Expensive Clothes

B.Taking Enough Money When Shopping

C.Being a Clever Clothes Shopper

D.Choosing the Labels inside New Clothes

填空题