[图] 1) Today you can no longer light up in the UK...

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??The human body naturally prevents attempt(企图)to lose or gain weight.Thus the best way to lower your weight is to do some exercise daily.Although scientists don&39;t agree exactly how this works to lower the“set point”,they do know that exercise helps your body work with you and not against you in at least the following ways：??

??1.Exercise burns calories(卡路里):if you walk two miles every day，you use an extra 1400 calories a week—??and lose about a pound in two weeks.??

??2.Exercise helps to bum fat and build muscle:since muscle requires more calories than fat does,the more muscle you have,the faster you will bum calories.????

??3.Finally exercise speeds up your metabolism(新陈代谢),not just while you&39;re exercising,but for several hours after exercise ends.??

??A program of light-to-moderate exercise done for only a half-hour a day is enough to keep your“set point”lowered,and thus helps you lose weight and keep it off.If you need to lose more than five pounds,combine regular exercise with a moderate reduction in calories until you reach your goal(目标).??

??Scientists don&39;t________.??

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A.think exercise helps people bodies work against them

B.agree exercise helps to lower people weight

C.believe in exercise at all

D.think exercise helps people bodies work with them

Exercise helps you________.A.save calories and gain weight

B.save calories but lose weight

C.bum calories and lose weight

D.burn calories but gain weight

Which of the following is NOT true?A.A man of more muscles burns calories faster.

B.Exercise speeds up your metabolism even after it.

C.An hour and a halls exercise is not enough to keep your“set point”lower

D.To lose more than 5 pounds，just doing exercise is not enoug

When you walk________.A.slowly，the fat in your body increases

B.1ess，you build more muscles

C.faster，you bum less calories

D.fast，the fat in your body reduces

请帮忙给出每个问题的正确答案和分析，谢谢！

图2.1中（）为并联。

A. R1与R2

B. R1与R3

C. R2与R3

D. R3与R4

一电路如图(1)所示，ε₁=12V，ε₂=9V，ε₃=8V，r₁=r₂=r₃=1Ω，R₁=R₂=R₃=R₄=R₅=2Ω。

图1-62所示电路中，已知：R1=R2=R3=R4=1Ω，Is=1A，Us=6V，求R4的电压。

如图16.1 所示, ξ1=3.0v,r1=0.5 Ω, ξ2=6.0 V,r2=1.0 Ω,R1=2.0Ω,R2=4.0Ω,求通过R1和R2的电流。

设R1和R2是集合A上的关系，且有R1  R2，则r(R1)  r(R2)。

如图11-3所示，1=3.0V,r1=0,5Ω,2=6.0V,r2=1.0Ω,R1=2.0Ω，R2=4，求通过R1和R2的电流。

放大电路如图所示，已知VCC＝12V，Re1＝1k，R1=R2=R3=Rc2=2k，VT1、 VT2的UBE=0.7V，、，足够大。（A、放大状态， B、截止状态， C、饱和状态） 1．VT1工作在 ； 2．VT2工作在 。

A、AB

B、CB

C、AC

D、CC

电路如题图9-6所示，已知：R1=30Ω，R2=R3=5Ω，L1=0.1H，C=1000μF，Us=140V，求uk(t)。

已知电路如图a所示，R₁=R₂=R₃=10Ω，试求R₂两端电压U。