右心衰竭最早的表现是 （）
A.恶心、呕吐
B.咯血
C.肝大
D.水肿
E.腹水
参考答案：C
Because the manager had some important guests to meet, the meeting only _____ a few minutes.
A．kept
B．continued
C．lasted
D．covered
研究对象静止于物体表面上，一定会产生静摩擦力。（）
