润滑油系统的作用不包括（）.
A、润滑
B、散热
C、紧固
参考答案：D
____ he has been chosen to work as a teacher in the mountain village ____ him feel very proud.
A．That, make
B．Whether, makes
C．That, makes
D．Where, make
难以通过血脑屏障的药物是由于其
A．分子大，极性低
B．分子大，极性高
C．分子小，极性低
D．分子小，极性高
E．分子大，脂溶性高
