与强心苷降低衰竭心脏的耗氧量无关的因素是
A.加强心肌收缩性
B.室壁张力下降
C.心脏的频率减慢,得到较好休息
D.心室容积减小
E.强心苷降低后负荷
参考答案:E
The reason for _______ he failed in the exam was that he was too careless.
A.which
B.why
C.that
D.it
在周长为60米的环形路道上种树,树的间隔为2米,则可种( )棵树。
A.30
B.25
C.31
D.29