胃痛主要与哪些脏腑有关
A．胃、肝、脾B．胃、脾、肾C．肝、脾、肾D．胃、肝、肾E．脾、胃、心
参考答案：A
The boy was so tired that he fell asleep ________ his mother could take off his clothes.[ ]
A. before
B. after
C. while
D. when
纳米是一种（）。
A.新材料
B.长度单位
C.微粒子
D.时间单位
