正常人脑脊液白细胞数为( )

A．＜10×10⁶/L
B．＜15×10⁶/L
C．＜20×10⁶/L
D．＜25×10⁶/L
E．＜30×10⁶/L

The policeman's attention was suddenly caught by a small box which ______  placed under

the Minister's car.

A. has been

B. was being

C. had been

D. would be