11. It is natural that____student doesn't know some answers to____questions raised by their teachers.

A．a;a

B．a;the

C．the;a

D．the; the

关于毛细血管采血法的叙述，下列哪项是正确的（ ）

A．耳垂采血时用强力挤压，取挤出的第一滴血液进行检查

B．耳垂血较静脉血的测定值低

C．用指端毛细血管血测定血红蛋白和白细胞计数结果比较恒定

D．婴幼儿首先的采血部位是耳垂

E．耳垂血结果较手指血稳定