液环式真空泵是利用叶轮的（）形成大小不同的空间来达到吸气和排气的。
A、运动
B、旋转
C、独特结构
D、偏心安装
参考答案：D
― Is Kate in, please? I want to ______ her.
― Sorry, she is out. You'd better ______ her later. [ ]
A. see; find
B. speak to; call
C. visit; ring up
D. talk to; look for
抑制性突触后电位的产生是由于突触后膜对下列哪种离子通透性增加所致
A．Na+、C1ˉ、K+，尤其是K+
B．Ca2+、K+、Clˉ，尤其是Ca2+
C．Na+、K+，尤其是Na+
D．K+、C1ˉ，尤其是C1ˉ
E．K+、Ca2+、Na+，尤其是Ca2+
