Although Mary will graduate from high school in June,she has not yet decided _____ a college.A.on B.about C.at D.toThe passengers were kept waiting in the hall for half an hour and then allowed _____ on another plane.A.to get B.getting C.them to get D.their getting

A.on
decide on 是词组.意思是 考虑后决定.这句话是说 尽管Mary将会在六月份从高中毕业,她还没有决定去哪一个大学.
其他的介词都不合理 decide about 和 at 没有这种用法
decide to do sth 是跟动词的
A be allowed to do sth 被允许做某事
固定搭配.

A A

A
on (an option) of colleges
A
and (they were) allowed to get on.....

1.A 意思是他还没决定要上哪所大学
2.B 意思是允许某件事发生

A
C

on “在什么方面”。 A 主语是passengers， be allowed to do sth 所以 A

a.decide on是固定的 a be allowed to do sth 是固定的

A 我也没听过decided about 、decided at
decide on 对什么做出决定
decide to do sth.动词短语
A 有allowed to do 也有allowed doing
这里有"and then" 是在提醒你，这是省略句
and then allowed to get on another plane.
即是and then they are allowed to get on another plane.

A
A

D A

1A decide on sth or decide to do sth 固定搭配
2.A 被动语态 be allowed to do sth

A.on
decide on 是固定搭配，决定做什么。
翻译：尽管Mary将会在六月份从高中毕业，她还没有决定去哪一个大学。
A
be allowed to do sth 被允许做某事
固定搭配。