人体处于何种体位时，外半规管与地面垂直（）。
A.直立位
B.平卧位
C.直立位头前倾30°
D.平卧时头前倾30°
E.直立位头后仰30°
参考答案：C
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______ your timely warning, we would have been unaware of the danger.
A．In spite of
B．But for
C．Instead of
D．As for
I was about to leave my house______ the telephone rang.
A．while
B．as
C．when
D．and
