小敏同学是近视眼,她的奶奶是远视眼,现有两副眼镜a、b,a上标有+200°,b上

题型:实验题

问题:

小敏同学是近视眼,她的奶奶是远视眼,现有两副眼镜a、b,a上标有+200°,b上标有-250°,则小敏和奶奶分别应佩戴哪副眼镜?这两副眼镜的焦距分别是多少?

考点:近视眼及其矫正远视眼及其矫正
题型:实验题

从中药水煎液中萃取有效成分可使用丙酮做溶剂。

题型:实验题

根据句意或句子的语法要求,用括号中所给词的适当形式填空。

小题1:It seemed that the victim had several          (enemy).

小题2:The story          (it) is wonderful, but the actor doesn’t act well.

小题3:So far, the police         (catch) several suspects of the crime.

小题4:Be quiet! We         (not allow) to make much noise in the reading room.

小题5:As an excellent teacher, she devoted most of her time to         (teach) her students.

小题6:There is a risk of being killed here, so we will move to another place for         (safe).

小题7:Most people hate wars, we want to live          (peace) in the world.

小题8:My little sister was very sad because of her favourite dog’s      (die).

题型:实验题

电台的执照应放在().

A.能立即出示之处

B.报房内

C.驾驶台

D.船长房间

题型:实验题
冬天室内温度是17℃,室外温度是-19℃,那么室内温度比室外温度高______℃,在-
2
3
、-3
1
4
、1.5、-1
1
2
中,最大的数是______,最小的数是______.
题型:实验题

软横跨节点8用于软横跨绝缘分段。

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