题干

某学校有300盏“220V 40W”的灯,其中“40W”表示 ____ ;若少开几盏灯,电路中的总电阻将 ____(选填“变小”、“不变”或“变大”).若这300盏灯每天少开1小时,共可节约电能  ____ 千瓦时.

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答案(点此获取答案解析)

该灯的额定功率为40W,变大,12

同类题2

根据短文内容,从短文后的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。

      It's normal to wake briefly during the night. ____ But if you're waking up duringthe night and having trouble falling back asleep, the following tips may help.

     Stay out of your head. The key to getting back to sleep is continuing to prepareyour body for sleep, so remain in bed in a relaxed position. Hard as it may be,try not to stress over the fact that you're awake, because that very stress andanxiety encourage your body to stay awake. ____

____If you are finding it hard to fall back asleep, try a relaxation technique suchas visualization(想象),or deep breathing, which can be done without even getting out of bed. Remindyourself that although they're not a replacement for sleep, rest and relaxationstill help refresh your body.

    Do a quiet, non-stimulatingactivity. If you've been awake for more than 15 minutes, try getting out of bedand doing a quiet, non-stimulatingactivity, such as reading a book. Keep the lights dim so as not to think thatit's time to wake up. ____  A light snackmight relax you, but be careful not to eat so much that your body begins toexpect a meal at that time of the day.

____If you wake during the night feeling anxious about something, make a brief noteof it on paper and delay worrying about it until the next day when you arefresh and it will be easier to resolve.

a.Make relaxation your goal, not sleep.

b.Put off worries and troubles.

c.Use a flashlight to go to the bathroomat night.

d.In fact, a good sleeper won't evenremember it.

e.Also avoid screens of anykind—computers, TVs, cell phones, iPads.

f.You'll be much more productive andcreative after a good night's rest.

g.A good way to stay out of your head isto focus on the feeling in your body.