Attandances at basketball matches have____ since the coming of television.
A. dropped in
B. dropped down
C. dropped off
D. dropped out
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当对正态总体均值检验时,如果总体方差未知则应该进行()。
A. Z检验
B. F检验
C. t检验
D. X2检验
淡水淹溺时血容量增加,血中主要电解质变化是钠降低,钾升高。()
A.In additionB.For exampleC.Above allD.After all
A. In addition
B. For example
C. Above all
D. After all
血液透析需要使用抗凝剂以防止透析器和血管通路凝血,常用的有肝素化抗凝法、低分子量肝素抗凝法、无肝素透析。()