特发性血小板减少性紫癜作骨髓穿刺的目的是

A．证明有血小板减少
B．了解骨髓增生程度
C．了解有无合并缺铁性贫血
D．了解巨核细胞数量及有无成熟障碍
E．证明有血小板抗体存在

Gasoline tanks should be filled（）.

A.to the top to expel all vapors from the tanks

B.to the top so the operator is certain how much fuel he has aboard

C.with only sufficient fuel for the planned trip so excess gasoline is not carried

D.to near the top with some space allowed for gasoline expansion