1.选择题- (共12题)
民航客机一般都有紧急出口,发生意外情况的飞机紧急着陆后,打开紧急出口,狭长的气囊会自动充气,生成一条连接出口与地面的斜面,如图所示,人员可沿着斜面滑行到地上.若机舱口下沿距地面3.2m,气囊所构成的斜面长度为4.0m,一个质量60㎏的人沿气囊滑下时所受到的阻力是240N,人滑至气囊底端时速度有多大?(g=10m/s2)
民航客机一般都有紧急出口,发生意外情况的飞机紧急着陆后,打开紧急出口,狭长的气囊会自动充气,生成一条连接出口与地面的斜面,如图所示,人员可沿着斜面滑行到地上.若机舱口下沿距地面3.2m,气囊所构成的斜面长度为4.0m,一个质量60㎏的人沿气囊滑下时所受到的阻力是240N,人滑至气囊底端时速度有多大?(g=10m/s2)
图为某种鱼饵自动投放器中的投饵管装置示意图,其下半部AB是一长为2R的竖直细管,上半部BC是半径为R的四分之一圆弧弯管,管口沿水平方向,AB管内有一原长为R、下端固定的轻质弹簧.投饵时,每次总将弹簧长度压缩到0.5R后锁定,在弹簧上端放置一粒鱼饵,解除锁定,弹簧可将鱼饵弹射出去.设质量为m的鱼饵到达管口C时,对管壁的作用力恰好为零.不计鱼饵在运动过程中的机械能损失,且锁定和解除锁定时,均不改变弹簧的弹性势能.已知重力加速度为g.求:
图为某种鱼饵自动投放器中的投饵管装置示意图,其下半部AB是一长为2R的竖直细管,上半部BC是半径为R的四分之一圆弧弯管,管口沿水平方向,AB管内有一原长为R、下端固定的轻质弹簧.投饵时,每次总将弹簧长度压缩到0.5R后锁定,在弹簧上端放置一粒鱼饵,解除锁定,弹簧可将鱼饵弹射出去.设质量为m的鱼饵到达管口C时,对管壁的作用力恰好为零.不计鱼饵在运动过程中的机械能损失,且锁定和解除锁定时,均不改变弹簧的弹性势能.已知重力加速度为g.求:
2.单项选择- (共18题)
A.a, the | B.a, a | C.the,/ | D.a,/ |
—Sorry, I have an important meeting to .
A.attend; join | B.join; attend |
C.join; take part in | D.join in; attend |
A.seen | B.to be seen | C.seeing | D.to see |
A.add up | B.add in | C.add up to | D.add to |
A.bringing back | B.looking up | C.trying on | D.referring to |
A.was built | B.being built | C.built | D.to be built |
A.to take | B.to be taken | C.taking | D.being taken |
A.gone up | B.goes up | C.going up | D.being gone up |
A.similarly | B.completely | C.likely | D.absolutely |
A.common | B.ordinary | C.normal | D.usual |
A.disappointing; disappointing |
B.disappointed; disappointing |
C.disappointing; disappointed |
D.disappointed; disappointed |
A.in exchange for | B.in return | C.in change for | D.in need of |
A.Compared | B.Compare | C.Comparing | D.To compare |
A.that has | B.have |
C.that have | D.what has |
A.that is the best film of the year? |
B.is the best film of the year? |
C.that the best film of the year is? |
D.the best film of the year is? |
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【1】题量占比
选择题:(12道)
单项选择:(18道)
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【2】:难度分析
1星难题:0
2星难题:0
3星难题:0
4星难题:1
5星难题:0
6星难题:17
7星难题:0
8星难题:0
9星难题:0