在心室扩大、泵血功能减退早期宜选用的评定指标是
A.搏出量B.心排出量C.射血分数D.静息心指数
参考答案:C
-It's hot today. Why don't you go swimming with me?
-_________[ ]
A. Nice to meet you
B. Here you are
C. The same to you
D. Good idea
每次强化所要求的反应数目不是固定的,而是不可预测地变化着,这种强化叫( )
A.区别强化
B.固定比例强化
C.可变比例强化
D.连续强化