单间客房年检查保养频率为（）次。
A.1-2
B.2-3
C.4-5
D.4-6
参考答案：D
一般显示脑组织常用的窗宽是
A．-30～-40
B．30～40
C．70～100
D．100～250
E．350～600
You can always _____ a dictionary if you meet new words during your English study. [ ]
A. set up
B. come to
C. turn to
D. get to
