Mike lost the pen                      he paid 10 yuan.

A．to which

B．which

C．for that

D．for which

药物分子依靠其在生物膜两侧形成的浓度梯度的转运过程称为（）

A．简单扩散

B．主动转运

C．首过消除

D．肝肠循环

E．易化扩散