人体各部分组织的电阻，以（）的电阻为最大。
A.皮肤
B.内脏
C.血液
D.四肢
参考答案：A
You can't use the machine today because some parts_____ this week. [ ]
A. are replaced
B. are being replaced
C. have replaced
D. are replacing
至今在八达岭陡崖上留下的古人题的字的内容是什么？
