题干

下列实验操作(或方案)不能达到实验目的是(   )

序号

实验操作(或方案)

实验目的

A

取两块干燥的玻璃片,对着其中的一块哈气

比较呼出的气体和空气中水蒸气的含量

B

向试管中加入2mL浓氨水,将蘸有酚酞溶液的棉花靠近该试管的管口

证明分子在不断运动

C

把燃着的木条伸入充满氮气的集气瓶里

探究氮气是否支持燃烧

D

用排水法收集气体,当导管口有气泡放出时,立即将导管伸入盛满水的集气瓶中

收集纯净的气体

A:A  

B:B  

C:C  

D:D

上一题 下一题 0.0难度 选择题 更新时间:2018-01-17 08:21:43

答案(点此获取答案解析)

D

同类题3

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    Have you ever noticed how terrible weather seems to drag your spirits down?____But there are various things you can do to keep your spirits up until spring.

    ____

    A snowy, icy, cold, or rainy world can be beautiful and often has sounds and smells of its own. If you're an artist, or photographer, winter provides a great deal of inspiration and different colors to work with. Even if you don't feel that creative, simply watching a winter scene from the comfort of your home can be a pleasant way to relax and enjoy the peace.

    Take part in winter activities.

    ____ If you're a beginner to these snow sports, try learning in areas where you won't be worried about more experienced people crowding you out. Local parks are ideal starting points to encourage you to get out and give new winter sports a go.

    ____

    Winter comes with the shortest days and lowest light of the year. Go out if you can. If you can't, or if you're so far from the equator as to have little or no daylight, use bright lights and perhaps light or white walls.

    Stay active.

    As much as possible, get yourself outside. Take at least a short walk. If the weather does not permit, move around inside. Walk up and down your stairs if you have them____ It also regulates such things as sleep and diet. Move around at least a bit each day.

A. Go out.

B. Brighten up.

C. Find things to enjoy about winter.

D. Enjoy skiing, sledding, or ice-skating.

E. There's nothing you can do about the weather.

F. Making snowmen is a fun activity for both kids and adults.

G. Exercise gets your body temperature up and your blood flowing.