问题 不定项选择

如图甲所示线圈的匝数n=100匝,横截面积S=50cm2,线圈总电阻r=10Ω,沿轴向有匀强磁场,设图示磁场方向为正,磁场的磁感应强度随时间作如图乙所示变化,则在开始的0.1s内

[ ]

A.线圈中磁通量的变化量为0.25Wb

B.线圈中磁通量的变化率为2.5×10-2 Wb/s

C.a、b间电压为0

D.在a、b间接一个理想电流表时,电流表的示数为0.25A

答案

BD

单项选择题
阅读理解

Spring is here and so is the cycling season. Here are some tips on how to do it safely and comfortably.

Watch your feet—Pushing with the wrong part of the foot can raise your risk of developing a painful injury of the heel and arch(脚心), says Rob Werstine, a sports physiotherapist(理疗师)and board member of the Canadian Physiotherapy Association.  You should push with the ball of your foot, he says.

Layer up—While it’s still cool, wear layers of clothing, with clothing close to the body that breathes and outer layers that do not absorb water. Go for bright colors that increase your visibility(可见度).

Be reasonable—If you are just starting out and aren’t in good shape, don’t sign up for a 50-kilometre ride. And while cycling is great exercise for people who want to get into shape, if your doctor advises you not to do tiring exercise, cycling shouldn't be your starting position, Werstine says. Walk to begin getting into shape and then graduate to cycling.                           

Fix the fit—If you develop lower back pain or numbness in your hands and fingers from cycling, it could be your bike isn’t adjusted properly for your height. A good cycle shop can help you find the right height for the seat and handlebars, but if you have continuing problems, consider consulting a bike fit physiotherapist, Werstine says.

Be mindful—You have to pay attention on the roads to vehicles, other cyclists and pedestrians(行人).Consider taking a cycling safety course to practise your skills. Or do some reading about how to avoid dangerous cycling situations. bicyclesafe.com, for instance, lists 10 types of car-bike accidents and how to avoid them.

小题1:Which part of the foot should one use when cycling?

A.The heel.

B.The arch.

C.The ball.

D.The toes.小题2: From Paragraph 4 we can conclude______.

A.not everyone can exercise by cycling

B.walking is better than cycling

C.cycling is popular with people

D.cycling is helpful to everyone小题3:According to the last paragraph, if you want to avoid danger when cycling, you should ______.

a. consider taking a cycling safety course

b. search for information on bicyclesafe.com

c. consider consulting a bike fit physiotherapist

d. adjust the bike properly for your height

A.a. c

B.c. d

C.a. b

D.b. d