成像变模糊的原因有()
A. 衍射时波长的限制
B. 成像透镜大小的限制
C. 卷积效应
D. 干涉效应
4f空间滤波系统需要完成从空域到频域,又从频域到空域的两次傅里叶变换过程。( )
周期函数的频率取值是连续的,所以周期函数只有连续谱。( )
Why does Zheyu Liu (刘哲瑜) want to learn English well?
A. He wants to communicate better with his friends.
B. He wants to go abroad to study.
C. He loves to learn English.
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