问题 选择题

下面说法正确的有(  )

①圆柱的底面积一定,它的体积与高成正比例.

②如果y=4x,y和x成反比例.

③如果小麦的出粉率一定,小麦的重量和面粉重量成正比例.

④长方形的周长一定,它的长和宽成反比例.

A.①②

B.①③

C.②④

D.③④

答案

①因为圆柱的体积公式V=sh,则s=V÷h,

所以,圆柱的底面积一定,它的体积与高成正比例;原题说法正确;

②如果y=4x,则y:x=4,

所以,y和x成正比例;原题说法错误;

③因为,小麦的出粉率=

面粉的重量
小麦的重量
×100%,

所以,如果小麦的出粉率一定,小麦的重量和面粉重量成正比例;原题说法正确;

④因为,长方形的周长C=(a+b)×2,

所以,长方形的周长一定,长与宽不成比例;原题说法错误;

故选:B.

完形填空

根据短文内容,从A、B、C、D和E中选出最适合填入短文空白处的选项。

A. It can protect your brain from being hurt in a bike accident

B. Go for bike rides with your kids so you can show them what safe riding looks like

C. Never wear ear-phones while biking

D. You have to choose good shoes 

E. Check your child’s bike to keep it safe and in good condition

Bike Safety

Bike riding is a great way to get exercise and fresh air and share time as a family. But before your kids rush out and start biking, there’s an important thing you need to consider —safety.

Helmet(头盔)Basics

Always wear a helmet when riding a bike, no matter where you are or how short the ride is. 小题1:______________________. Here’s why: Many bike accidents mean brain damage or death for someone who does not wear one while riding. To protect against brain injury, make sure your kids wear a correctly fitting helmet on every ride.

Safe Clothing

What kids wear when riding a bike is also very important for safety. Bright-colored clothes will help kids be visible on the road. Besides, 小题2:____________________. Kids should never ride barefoot(赤脚)!

Rules of the Road for Bike Riding

Here are some must-know safety tips to teach kids:

·Stop at all stop signs and obey traffic lights just as cars do.

·Always stop and check for traffic in both directions when leaving a driveway.

·小题3:_______________________. It’s important to hear everyone else on the road.

Making Safety a Family Activity

One of the best ways to help kids learn safe bike riding is to set a good example by following the rules of the road yourself. 小题4:_________________________. It’s also a great way to stay active as a family and spend valuable time with your kids!

单项选择题