下列哪种昆虫在发育过程中经历“若虫”这个时期[ ] A.椿象 B.蚂蚁 C.蝇

题型:选择题

问题:

下列哪种昆虫在发育过程中经历“若虫”这个时期[ ]

A.椿象

B.蚂蚁

C.蝇

D.蚯蚓

考点:昆虫的生殖和发育
题型:选择题

如图所示,V1和V2是完全相同的两个电压表,都有3V和15V两个量程,闭合开关后,发现两个电压表偏转的角度相同,则在相同时间内,电流通过电阻R1和R2产生的热量Q1∶Q2=     

题型:选择题
The Huntington Library Hours
The Huntington is closed on Thanksgiving, Christmas EVE, Christmas Day, New Year’s Day, and Independence Day.
From November 1st to Labor day, The Huntington observes summer hours and is open from 10:30 a.m.– 4:30 p.m. daily, except Tuesdays. (After Labor Day, hours are 12 noon – 4:30 p.m. on Mon., Wed., Thurs. and Fri.; 10:30a.m. - 4:30 p.m. on Sat. and Sun.; closed on Tues.)
Admission
Reservations are not necessary to visit The Huntington. Tickets may be purchased at the time of your visit.
 
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Weekends
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$20
$23
Seniors ( age 65+ )
$15
$18
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$8
$8
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free
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$11 ( per person )
$14 ( per person )
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Parking is free at The Huntington. And no parking reservations are necessary unless you are a school or tour group arriving by bus.
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小题1:If next Saturday a 66-year-old man goes to the library with his three grandchildren, aged 4, 6, 14, how much should he pay?
A.$40.B.$39.C.$35.D.$44.
小题2:To visit the library on free days, you_______.
A.get free tickets on arriving at the library
B.must reserve a parking place
C.have to buy admission tickets
D.should reserve tickets in advance
小题3:As for tour groups arriving at the library by bus, ________ .
A.they have to pay for the parking space
B.they don’t need to make a reservation
C.they should call the library in advance
D.they have to park their bus outside
题型:选择题

如图所示,质量M = 1kg的木板静止在粗糙的水平地面上,木板与地面间的动摩擦因数μ1=0.1,在木板的左端放置一个质量m=1kg、大小可以忽略的铁块,铁块与木板间的动摩擦因数μ2=0.4,取g=10m/s2,试求:

(1)若木板长L=1m,在铁块上加一个水平向右的恒力F=8N,经过多长时间铁块运动到木板的右端?

(2)若在木板(足够长)的右端施加一个大小从零开始连续增加的水平向左的力F,请在图中画出铁块受到的摩擦力f随力F大小变化的图像。

       

题型:选择题

电液换向阀不能回中的原因不包括()。

A.回中弹簧失效

B.控制油路中某侧节流阀未开

C.油液污染严重,阀芯卡阻

D.某侧电磁线圈断路船舶辅机

题型:选择题

临床不会导致月经先期的是()

A.气虚不摄

B.肝郁血热

C.营血亏损

D.阴虚火旺

E.阳盛血热

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