在如图16-5-9所示的电路中，D1和D2是两个完全相同的灯泡，其额定电压在数值

发布时间：2017-06-25 16:40 │ 来源：www.tikuol.com

题型：选择题

问题：

在如图16-5-9所示的电路中，D₁和D₂是两个完全相同的灯泡，其额定电压在数值上约等于电源电动势，电源内电阻可以忽略不计，L是一个自身电阻可以忽略不计而自感系数足够大的线圈.若开关S₂断开、S₁闭合，两个灯泡都发出较暗的光.若闭合S₂，两个灯的亮度变化情况是( )

图16-5-9

①D₁逐渐变亮，后来亮度稳定 ②D₁逐渐变暗，后来熄灭 ③D₂逐渐变亮，后来亮度稳定 ④D₂逐渐变暗，后来熄灭

A．①②

B．②③

C．③④

D．②④

考点：自感现象

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完型填空。

     Do you like Dolphins (海豚)? Dolphins live   1   water, but they are not fish. They are mammals (哺乳
动物) that live in water. It has to (不得不) breathe (呼吸) air to the top of the water very often. A dolphin's
nose isn't   2   to see. It's just a very   3   hole on top of the dolphin's head. This hole is called a blowhole. A
dolphin   4  up every minute or so to breathe. It opens blowhole and takes air in, and then goes back into the
water again. It can stay   5   the water for six or seven minutes if it has to. A dolphin's ears are very small,
  6   its mouth is very   7 . It has almost one hundred teeth. A dolphin   8   very fast. Scientists are studying
ways to   9   boat go faster through the  10 .

( )1.A. in
(    )2.A. easy
(    )3.A. small
(   )4.A. goes
(    )5.A. at
(    )6.A. if
(    )7.A. small
(    )8.A. goes
(    )9.A. make
(    )10.A. air

B. on
B. difficult
B. big
B. comes
B. up
B. or
B. big
B. swims
B. ask
B. room

C. above
C. good
C. smaller
C. walks
C. on
C. but
C. good
C. runs
C. tell
C. land

D. under
D. fast
D. bigger
D. runs
D. under
D. so
D. nice
D. walks
D. talk to
D. water

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工程咨询公司以分包商的角色进行工程咨询服务的时候，其直接服务的对象是 ( )。

A．总承包商
B．项目法人
C．贷款银行
D．项目业主委托的总设计单位

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A．were chasing

B．was chasing

C．chased

D．were on a chase

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