房室延搁的生理意义是
A.使心室肌不会产生完全强直收缩
B.增强心肌收缩力
C.使心室肌有效不应期延长
D.使心房、心室不会同时收缩
E.使心室肌动作电位幅度增加
参考答案:D
________ some students are not aware of is ________ difficult life can be if they are not devoted to study.
A.That; how
B.Which; what
C.What; what
D.What; how
混凝土结构()是城市桥梁工程新规程CJJ2-2008修订中要解决的一个重要问题。