A.Cousins.B.Aunt and nephew.C.Niece and uncle.D.A client and a secretary.
A. Cousins.
B. Aunt and nephew.
C. Niece and uncle.
D. A client and a secretary.
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劳务报酬收入一次性超过20000元的应加成征税。()
A. 正确
B. 错误
在骨骼肌兴奋一收缩耦联中起关键作用的离子是
A. Na+
B. K+
C1-
D. Mg2+
E. Ca2+