题干

飞机跑道的设计与当地盛行风向关系密切,一般而言,飞机起飞时,机翼获得升力的大小取决于飞机与空气的相对速度,而不是飞机与地面的相对速度。相对速度越大。升力越大。越容易起飞。飞机降落时。又需要借助风速缩短滑跑距离。下列关于飞机起落方向及机场建设,说法可信的是(   )

①顺风起飞获得的升力较大、有利于起飞  ②逆风降落有利于减缓飞机飞行速度、利于降落  ③空气稀薄地区,飞机起降时与空气产生的摩擦力较小,因此,可适当延长飞机跑道距离  ④一般而言、机场地形坡度越小越好

A:①②

B:②③

C:①③

D:②④

上一题 下一题 0.0难度 选择题 更新时间:2013-03-04 07:08:10

答案(点此获取答案解析)

B

同类题1

根据短文内容,从短文后的A—G选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    Many of us deal with the rush every morning in preparation for work or school, but it doesn't have to be this way. With a little time management, these steps can help you cut down on your morning stress.

Create an evening preparation routine

    ____ These simple tasks will take you less than 30 minutes to complete each evening and will save you a huge headache every morning.

Get a good night's sleep

    Make sure you go to bed at a reasonable hour to allow enough time for a healthy night's sleep. Most people require between seven and eight hours' sleep each night. If needed, set a bedtime reminder alarm on your alarm clock.____

Wake up 30 minutes earlier

    An extra 30 minutes in the morning will make a difference. As long as you get to bed on time, waking up 30 minutes earlier should seem natural after just a few days.____

Plan a realistic day

    Writing things down means you don't have to worry about forgetting to do them.____ Write down anything that cannot be put off to following day.

____

    Getting up to face a new day is far more satisfying when you have something to look forward to. Make sure you manage your time better so that you have time to do something you love on a daily basis.

A.Morning stress is very common.

B.Schedule something you love daily.

C.Never fill your mind with unnecessary worries.

D.Make a summary of what you did in the daytime.

E.Use this time to think, shower and eat breakfast.

F.Iron your clothes, locate your keys, plan a nutritious breakfast, etc.

G.Always keep the temperature in your bedroom comfortably cool.