After an(introduce)______by the chairperson,we’ll go on with the day’s discussion.请问上面句子的空格处应该填入什么词性?
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I’m afraid there is not much (differ) ____________ in their points of view.请问上面句子的空格处应该填入什么词性?
A. 名词
B. 动词
C. 形容词
D. 副词
John felt very (disappoint)_______________ when his boss turned down his proposal.请问上面句子的空格处应该填入什么词性?
A. 名词
B. 动词
C. 形容词
D. 副词
用每毫米内有400条刻痕的平面透射光栅观察波长为589nm的钠光谱。试问:光垂直入射时,最多能观察到几级光谱?
A. 4
B. 3
C. 5
D. 6
用每毫米内有400条刻痕的平面透射光栅观察波长为589nm的钠光谱。试问:光以300角入射时,最多能观察到几级光谱
A. 4
B. 3
C. 5
D. 6