婴儿期白细胞总数维持在（）

A.>20×10⁹/L

B.15×10⁹/L

C.10×10⁹/L

D.5×10⁹/L

E.<5×10⁹/L

When asked about his result of the driving test, David said with a big smile that he

had         .

A．got through

B．got up

C．got on

D．got out