集体名词的动词单复数形式这句话（自己造的,不一定对）：We ask people who does not come here the reason why they do not come.这里应该是people who does not还是people who do not?同样,后面用they do not合适吗?然后,如果把上面的people改成everyone,后面的they do not又可以吗?

It should be:
We ask people who do not come here the reason why they did not come.
这里应该是people who do not come

集体名词的动词单复数形式：
回答：
1）
请先看下关于“集体名词的动词单复数形式”：
英语中有些集体名词，如：people, police, cattle等，通常当作复数看待，其后的谓语动词必须用复数。
如：
There were many poeple present at the sports meet. 有许多人参观了运动会。
The police are searching for the two bandits. 警察正在搜查两个匪徒。
The cattle are grazing in the fields. 一群牛在田野里吃草。
2)
所以原句中，应该是people who do not, 而不是people whoes do not；
3）
复合不定代词（如：everyone等），作主语时，谓语动词用单数形。
如：
If everyone is ready, we'll begin.
Where is everyone?
关于‘复合不定代词’，语法家们的意见虽不完全一致，但普遍都认为everyone和everybody是单数，尽管everyone听起像是很多人，可是 Everyone are happy.是错误的；
你如果把上面句子里的people改成everyone，后面的they do not 则须改为：he/she doesn't come;
4)
原句的改换：
We ask people who does not come here the reason why they do not come.
We ask everyone who doesn't come here the reason why he/she doesn't come.
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英语句子表达,既要注意主谓一致,又要兼顾时态.因此,你给的句子要修改成：
We ask people【 who did not come here the reason】 why 【they did】 not come.
We ask everyone【 who did not come here】 the reason why【 they did 】not come.
说明：they后面一般现在时态,都是用【复数形式】.
集体名词单复数情况变化分类：
1、只当作复数看待的名词,谓语动词自然使用复数：
people(人)（做“民族”时,复数形式是peoples）,police,cattle,staff 等.
2、单复数形式取决于单词表达意义的常见词：
class,group,team,family,government等,当表示组织单位时,当作单数看待；表示组织单位中的成员时,当作复数看待.例如：
His family is large.
The family are watching TV.
3、everyone,everybody等不定代词,在上下文使用人称代词指代时,为了使用方变,经常使用they,代替his or her.例如：
We ask everyone if they have their own learning methods.
祝你开心如意!