—Our environment is getting worse than before.

—You're right. But people have done more and more

    useful things to protect (保护) the earth since Earth Day _____. [ ]

A. is started

B. was started

C. has started

应根据下列哪项来合理选择血管活性药物（）。

A.血压的高低

B.心跳的快慢

C.休克的类型和阶段

D.患者的神志情况

E.尿量的多少