患者男，55岁，因“全身骨骼肌易疲劳，吞咽困难，屈颈抬头无力，四肢乏力1个月”来诊。诊断：重症肌无力。

重症肌无力的临床表现有（）。

A.起病隐匿，病情进展缓慢

B.多数患者眼外肌最先受累

C.继之颈肌及四肢近端肌群受累

D.最后累及咽喉肌、呼吸肌

E.有“晨轻暮重”的现象

F.胆碱酯酶抑制药治疗有效

He appears to be strong and healthy, but, ____ he suffers from a very weak heart. [ ]

A. in other words

B. on the other hand

C. as a matter of fact

D. for one thing