脑屏障包括（）。
A.血-脑屏障
B.血-脑脊液屏障
C.硬脑膜
D.颅骨
E.脑脊液-脑屏障
参考答案：A, B, E
Li Gang was required to apologize ____ the people present at the meeting _____ what he had done. [ ]
A. for; by
B. with; about
C. to; for
D. at; with
A．+→
B．→+
C．+→
D．→+
+
→
→
+
+
→
→
+
