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你有仔细观察过家中物理现象吗？家中用久了的白炽灯泡，它的发光亮度跟刚买时相比，是亮一些还是暗一些？请用学过的电学和热知识说明其中的原因．

答案

答：暗一些．原因是白炽灯泡的灯丝，用久了会升华变细，导致电阻变大，当电压不变时，电流变小，根据P=UI得，实际功率则变小了，所以灯泡变暗．

阅读理解

（1）
Lad and Lassies Play School
2902 N. W. 22nd Place                       375---7742
Land Clearing Service
RFD Millville                              462---1606
Lannon’s Real Estate
905S.E.2nd Terrace                         376---8668
Larry’s Pools Inc.
4100 Oak Strcet                           377---4276
London Recreation Club
2L4S. 33rd Drive                          378---8432
 
( 2）
Adu1ts twelve years o1d and over take two teaspoonfu1s as needed，not to take over fifteen teaspoonfuls per day. Chi1dren six years old to twelve years old take half of the adult dosage（剂量），not to take over seven teaspoonfuls per day.
Do not take more than the recommended dosage un1css directed by a physician．Not to be used by children under six years old. Nor by persons with high blood pressure，heart disease, or diabetes（糖尿病）.
This preparation may cause drowsiness. Do not drive or operate machinery while taking this medication.
Chronic（长期的）cough is dangerous. If relief（缓解）does not occur within three days，discontinue use and consult your physician.
小题1:Which number would you call丘f you were looking for a house or an apartment？
A．375－7742B．376－8668C．462—L606D．378—843257
小题2:Which address would you give to your friends if they wanted to play tennis？
A．RFD MillvilleB．905 S.E. 2nd Terrace
C．214 S.33rd DriveD．4100 Oak Street
小题3:According to the directions, which of the following people should take the medication described？
A．Someone with high blood pressure.B．Someone with diabetes or heart disease.
C．Someone under six years old.D．Someone who has a cough.
小题4:If this medication does not help within three days, one should         .
A．take fifteen teaspoonfuls on the fourth day B．stop driving and operating machinery
C．take half of the usual dosageD．stop taking it and see a doctor
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单项选择题 B1型题

牙体缺损修复时如原有根尖周病未彻底治疗修复后会出现（）。

A.自发性痛

B.过敏性痛

C.咬合痛

D.龈炎

E.修复体松动
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