心力衰竭患者使用血管扩张剂的主要作用是
A．提高心肌收缩力B．改善冠状动脉循环C．减轻心脏的负荷D．减慢心率E．增加回心血量
参考答案：C
_________ he ________ many good friends?
A．Does , have
B．Do , have
C．Does , has
D．Are, have
. Tracy has gone abroad for further study. It ____ be her. The girl you saw yesterday is her sister.
A．may
B．shouldn’t
C．must
D．can’t
