如图所示,S1、S2是弦线两端的两个波源,它们的振动周期都为T,振幅都为A,某时

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问题:

如图所示,S1、S2是弦线两端的两个波源,它们的振动周期都为T,振幅都为A,某时刻S1发出的波恰好传到C,S2发出的波恰好传到A,且S1C=S2A,图中只画出了此时刻两列波在AC 之间部分的叠加波形,S1、A间和S2、C间波形没有画出,下列说法正确的是

[ ]

A.A、B、C三点是振动减弱点    

B.A、C是振动减弱点,B是振动加强点,振幅为2A

C.再经过T/4,AC间的波形是一条直线

D.再经过T/4,AC间的波形不是一条直线

考点:波的干涉
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以下正面投影成斜线的有()

Ⅰ.一般位置线;

Ⅱ.正垂面;

Ⅲ.正平线。

A.Ⅰ

B.Ⅰ+Ⅱ

C.Ⅰ+Ⅲ

D.Ⅰ+Ⅱ+Ⅲ

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失恋问题适于( )。

A.团体咨询

B.现场咨询

C.个体咨询

D.专题咨询

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制约西北地区农业生产的主要因素是[ ]

A.地形条件

B.水源条件

C.光照条件

D.热量条件

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My first job was at a local restaurant, where I worked for seven years and learned so many lessons, especially from a fellow  36 .
Helen was in her 30s and had extraordinary self-confidence, something I was really  37 . I looked up to Helen  38 she was doing what she loved—  39 people better. She always made everyone, customers and co-workers,   40 and feel good.
Being a waitress changed my life. One of my  41 customers was Fred Hasbrook. He always ate an omelet, and when I saw him _42 , I tried to have it on his table as soon as he sat down.
Thanks to the newfound confidence I  43  __from Helen, I dreamed of having my own  __44 . But when I called my parents to ask for a loan, they said, “We just don’t have the money.”
The next day, Fred saw me and asked, “What’s  45 ? You’re not smiling today.” I  __46__my dream with him and said, “Fred, I know I can do more if somebody  47 just have faith in me.”
Before long he handed me checks  48  __$50,000—along with a note that I have to this day. It reads, “The only collateral(抵押品)on this loan is my trust in your  49 as a person. Good people with a dream should have  50  __to make that dream come true.”
I took the checks to Merrill Lynch, where the money was provided for me. I_ 51 __working at the restaurant, making  52 for the restaurant I would open. My plans soured, though, and I lost the  53 .
Later I decided to apply for a job at Merill Lynch. Even though I had no experience, I was__54 and ended up becoming a pretty good agent.   55 . I paid back Fred the $50,000, plus 14-percent annual interest. Five years later, I was able to open my own firm.
小题1:
A.friendB.waitressC.citizen D.customer
小题2:
A.losingB.earningC.sharingD.lacking
小题3:
A.whileB.thoughC.becauseD.unless
小题4:
A.serving B.respectingC.helpingD.praising
小题5:
A.workB.eatC.smileD.speak
小题6:
A.regularB.favoriteC.respectedD.fresh
小题7:
A.eatingB.greetingC.smilingD.coming
小题8:
A.found outB.picked upC.got backD.took away
小题9:
A.restaurantB.workC.houseD.money
小题10:
A.aheadB.thatC.thereD.up
小题11:
A.exchangedB.discussedC.sharedD.explained
小题12:
A.shouldB.wouldC.mightD.must
小题13:
A.totaling B.countingC.addingD.valuing
小题14:
A.abilityB.honestyC.responsibilityD.identity
小题15:
A.patienceB.confidenceC.choiceD.chance
小题16:
A.lovedB.practicedC.continuedD.enjoyed
小题17:
A.tablesB.plansC.decisionsD.suggestions
小题18:
A.faithB.honestyC.moneyD.friend
小题19:
A.hiredB.rejectedC.encouragedD.determined
小题20:
A.FortunatelyB.ExcitedlyC.PersonallyD.Eventually
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堆石坝碾压应采用错距法,按坝料分区、分段进行,各碾压段之间的搭接不应小于( )。

A.1.0m
B.0.5m
C.2.0m
D.0.3m

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