声音的传播速度和介质有关，声音在空气中传播速度约为（）m/s。
A.340
B.1500
C.3000
D.5590
参考答案：A
对于无症状HIV携带者进行免疫学检查的建议是（）
A.每3个月检查一次
B.每6个月检查一次
C.每年检查一次
D.每3～6个月检查一次
E.每6～12个月检查一次
The doctor suggested she ______ in bed, while her smiling face suggested there ______nothing serious.
A．stay, was
B．stayed, should be
C．staying, was
D．stay, should be
