两个完全相同的电热器,分别通有如图所示的交变电流,则它们的功率之比为( ) A

题型:选择题

问题:

两个完全相同的电热器,分别通有如图所示的交变电流,则它们的功率之比为(   )

A.4:1

B.1:

C.2:1

D.:1

考点:交变电流的周期和频率交变电流的最大值、有效值、瞬时值和平均值
题型:选择题

根据短文内容,将下列空白处补充完整,每空一词。

Children’s schooling is changing very fast today. In the past, teachers k____________(1) children sitting still for hours. They made them remember d_______________(2) kinds of things. In other w______________(3), The children had to go on repeating things until they knew them “by heart”. Today, many teachers want to know if it is p______________(4) to make children learn at all. They say you can o______________(5) help them learn. They say you must let children learn and find out things for t______________(6).

But foe these children, school is a kind of prison. They are there only because their p_____________(7) make them go. They get out of the classroom as soon as the teacher lets them l______________(8). Many of them want to find work, but the law will not let them work until they reach a certain a________________(9). And so, they have to stay in school. Often they do not learn anything at all and h________________(10) every moment in class.

题型:选择题

29岁,G1P0,卵巢恶性肿瘤患者。

患者术后加用化疗,出现肺间质纤维化,由于下列哪种化疗药物引起

A.环磷酰胺

B.顺铂

C.紫杉醇(紫素)

D.博来霉素

E.卡铂

题型:选择题
夏天是雷雨的多发季节,遇到雷雨天气时,以下做法正确的是(  )

A.躲在大树下避雨

B.撑着金属杆的雨伞在户外行走

C.冒雨在运动场上踢球

D.避免使用电话和手机

题型:选择题

《新婚别》《无家别》《垂老别》是哪位唐代诗人的经典作品?

题型:选择题

高频开关电源中,常用的电力电子器件为:()

A.GTR

B.MOSFET

C.IGBT

D.GTO

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