题干

2013年12月6日17时47分,在北京飞控中心工作人员的精密控制下,嫦娥三号开始实施近月制动,进入100公里环月轨道Ⅰ,2013年12月10日晚21∶20分左右,嫦娥三号探测器将再次变轨,从100公里的环月圆轨道Ⅰ,降低到近月点(B点)15公里、远月点(A点)100公里的椭圆轨道Ⅱ,为下一步月面软着陆做准备.关于嫦娥三号卫星下列说法正确的是(    )

A:卫星在轨道Ⅱ上A点的加速度小于在B点的加速度

B:卫星沿轨道Ⅰ运动的过程中,卫星中的科考仪器处于失重状态

C:卫星从轨道Ⅰ变轨到轨道Ⅱ,在A点应加速

D:卫星在轨道Ⅱ经过A点时的动能小于在轨道Ⅱ经过B点时的动能

上一题 下一题 0.0难度 选择题 更新时间:2018-07-16 06:28:39

答案(点此获取答案解析)

A,B,D

同类题3

根据短文内容,从短文后的七个选项中选出五个最佳选项填入空白处。

    As you're busy with your studies, the weeks during the Spring Festival can be a time when training and healthy eating plans go out of the window. But you can continue running and avoid weight gain during the holiday season. ____

Pick a race

    Having a race on your calendar is a motivation to keep running during the holiday. ____ Check our active.com or Running in the city for events near you.

Don't skip breakfast

    If you're going to a holiday party in the evening, don't make the mistake of skipping breakfast. You may think you're saving calories for later. ____

Bring your own healthy dishes

    Chances are that most of the dishes at holiday gatherings are going be high in taste and calories. Bring your own healthy appetizers to the party. The host will appreciate it, and you know where will be at least one wise choice on the buffet table.

____

    If you are heading to an evening event, eat regular meals and snacks every few hours until party time. You won't arrive at the party ready to attack appetizers. Make sure you include fiber at each meal because it keeps you full longer.

Plan your runs

    It's easy to say that you'll keep running regularly during the holiday season, but sticking to it requires a strategy. Schedule your runs like appointments, so you make them the first thing during a busy week. ____

A. Treat yourself

B. Eat small meals

C. Try some or all of these strategies.

D. In fact, it may lead to overeating later in the day.

E. Buy yourself a gift of some new running shoes and clothes.

F. If you have runs scheduled, you are more likely to get them done.

G. Once you choose one that is in a few weeks, set a plan and stick to it.