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【单选题】
关于点的投影,下列叙述正确的是A.
空间两个点，在一个投影面上必定有两个点。
B.
空间一个点，在一个投影面上的一个投影点就能决定空间点的位置。
C.
在正投影中，空间一个点在一个投影平面上仅有一个点的投影。
D.
在正投影中，空间一个点在一个投影平面上有时可有两个点的投影。
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【简答题】Writing: Suppose you are a close friend of the Elliott family. Write a letter of condolence(吊唁) to Pauline on the death of Frank. Write a letter of about 130 words.
【简答题】平行单色光垂直入射到平面衍射光栅上,若增大光栅常数,则衍射图样中明条纹的间距将 ,若增大入射光的波长,则明条纹间距将 。 (两空都填“增大”、“减小”或者“不变”)
【单选题】—Why! Where’s my mobile phone? Maybe I left it on the plane. —My goodness! You things behind.
A.
haven’t left
B.
didn’t leave
C.
had never left
D.
never leave
【单选题】A I was waiting for a phone call from my agent. He had left at message the night before, telling me that my show was to be cancelled. I called him several times, but each time his secretary told me th...
A.
He was mad at the telephone.
B.
He was angry with his agent.
C.
He was anxious about his wife.
D.
He was impatient with the secretary?
【单选题】My mobile phone disappeared. Where _____ I have left it?
A.
may
B.
must
C.
could
D.
should
【单选题】平行单色光垂直入射到平面衍射光栅上,若光栅常数从每毫米500条变成每毫米600条,则衍射图样中明条纹的间距将 ,若入射光从黄光变成红光,则明条纹间距将 。
A.
（1）增大 （2）增大
B.
（1）增大 （2）减小
C.
（1）减小 （2）增大
D.
（1）减小 （2）减小
【简答题】(1)Write the possible values of l when n=5. (2)Write the allowed number of orbitals (a) with the quantum numbers n=4，l=3；(b) with the quantum numbers n=4；(c) with the quantum numbers n=7，l=6，m=6；(d) w...
【多选题】平行单色光垂直入射到平面衍射光栅上，下列说法正确的是:
A.
若增大光栅常数，则衍射图样中明条纹的间距将变大
B.
若增大光栅常数，则衍射图样中明条纹的间距将变小
C.
若增大入射光的波长，则明条纹间距将变小
D.
若增大入射光的波长，则明条纹间距将变大
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