有限花序则是花序（）或（）先开，然后由顶向基或由内向外开放。
参考答案：顶端；中心花
Students were always interested in finding out_________they can go with a new teacher. [ ]
A. how far
B. how soon
C. how often
D. how long
重症肌无力表现为（）
A.眼外肌、面肌、延髓支配各肌最常受累
B.受累的肌肉持续无力
C.常有肌肉萎缩
D.抗胆硷酯药物无效
E.血钾偏低
