从胆汁中排出的药物或代谢物，在小肠中转运期间又重吸收返回门静脉的现象（）.
A．胃排空速率
B．肠肝循环
C．首过效应
D．代谢
E．吸收
参考答案：B
188. The truck is carrying a _____of bananas. All these will be sent to the north of China.
A．loaf
B．lid
C．load
D．Burdens
If you come，you must be prepared to keep moving，______ it is too cold to stand and watch for long.[ ]
A．as
B．when
C．if
D．unless
