在光栅中，单缝衍射所起的作用并不改变主极大明纹的位置，只影响各级主极大明纹间的光强分配。
查看答案
光栅衍射中，将光栅垂直会聚透镜光轴方向做微小的平移，则衍射图形会随之移动。
A. 对
B. 错
Learning about the great news, she was_excited to calm down.
A. much too
B. too much
C. so much
D. very much
They are teachers and don't realize to start and run a company.
A. what it takes
B. what takes it
C. what they take
D. what take they
I can't remember Benjamin wrote "Poor Richard“.
A. what
B. who
C. if
D. which
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