A:H2
B:2H
C:Fe
D:H2O
根据句意及首字母或汉语提示完成单词
① Lots of sports c____ are strict with the athletes.
②He is the winner at the 100-metre r____.
③ Zhang Yining is not an o____ success.
④ The ____ (广告)is very meaningful.
⑤Tom broke a ____ (纪录)in running.
细胞学说揭示了