肌无力危象（muasthenic crisis）
参考答案：
重症肌无力最常见的危象，因抗胆碱酯酶药量不足时引起呼吸困难甚至呼吸肌麻痹。
It's very difficult to learn English well, but you can't _____. [ ]
A. put it up
B. take it up
C. look it up
D. give it up
