机场灯光系统应当在航空器起飞后15分钟、着陆后（）分钟、或按照管制部门的通知关闭。
A.10
B.15
C.20
D.25
参考答案：A
— Did you see the girl in white pass by just now?
— No, sir. I a newspaper.
A．read
B．was reading
C．would read
D．am reading
超强刺激的强度应是比产生最大肌收缩效应的刺激强度还要增强（）
A.5%～9%
B.10%～15%
C.16%～29%
D.20%～25%
E.26%～30%
