提示单词:often, sometimes, always, never, once
Peter
Judy
Lucy
Lily
Sunday
√
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
如图所示,集气瓶内充满某混合气体,置于光亮处,将滴管内的水挤入集气瓶后,烧杯中的水会进入集气瓶,集气瓶内气体是( )