What's the correct expression of 化妆包?
A. cosmetics
B. cosmetic
C. cosmetics cases
D. cosmetic case
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Excuse me, did you see _______ keys?
A. a set of
B. a set
C. sets of
D. sets
I thought that the room attendant _________ where they went.
A. might see
B. might have seen
C. might saw
D. might have saw
动态滤波是()。
A. 补偿不同深度的衰减
B. 频率可控的选频网络
以下那个不是B超诊断成像的发射声束特点。( )
A. 单路发射
B. 对振子按不同顺序分组激励,形成不同波束扫描方式