moment they enrolled.是定于从句么 省略了that是么?能帮我讲讲么They have been studying hard from the moment they enrolled.\x05顺便问下vi可以加从句么

moment they enrolled.是定于从句么 省略了that是么?能帮我讲讲么
They have been studying hard from the moment they enrolled.
\x05顺便问下vi可以加从句么

句子(when) they enrolled虽然短小,但它已经具备了主语+谓语的句子要素了,是一个定语从句,因为先行词是表示时间的,故用关系副词when去引导这个定语从句,但关系词被省略了.vi是不及物动词,没有动作的承受者,就没有宾语,当然更不可以加宾语或定语从句,但因为动词可以被副词性从句,即状语从句所修饰,故它可以有各种各样的状语从句了.

这个句子有误吧，应该是They have been studying hard from the moment when they enrolled.
when they enrolled是定语从句，修饰the moment。
vi可以加从句，但不是定语从句。