已知直角三角形中30°角所对的直角边为3 cm，则斜边的长为 [ ]
A.3 cm
B.6 cm
C.8 cm
D. 9 cm
答案：B
17. -- My mother always tells me to try my best _______ many difficulties.
-- I can’t agree any more. _______ you put your heart into work, you can overcome them.
A．because of / As far as
B．due to / As soon as
C．in spite of / As long as
D．despite of / As much as
关于流行性出血热，下列哪项是错误的（）
A.流行性出血热病毒是一种RNA病毒
B.流行性出血热流行具季节性和周期性
C.流行性出血热的主要传染源是鼠类
D.流行性出血热的皮疹多为出血性
E.流行性出血热都具典型的五期经过
