it is at this time that students realize howit is at this time that students realize how much they need to learn and how little time they have to do it.想知道句子结构成分

主语students 谓语 realize ，宾语 how much they need to learn and how little time they have to do it. 前面it is at this time 是个强调句，是整个句子的时间状语，也就是说这个句子强调时间状语，直到这个时候，同学们才意识到他们还有多少东西要学，完成他们还剩下多么少的时间。

强调句

一、这是一个强调句,这里强调的是时间状语,具体结构为——
强调句式：it is ...that
时间状语：at this time
主语：students
谓语动词：realize
并列宾语从句：how much they need to learn and how little time they have to do it.
二、强调句总的结构是——
It is + 强调词语 + that + 其他部分
三、具体应用还可以分为——
1、强调主语：It is + 主语 + that + 谓语动词 + 其他部分.如：
It is students that realize at this time how much they need to learn.正是学生们在这个时候才意识到他们需要学多少.
2、强调其他成分：It is + 强调部分 + that + 主语 + 谓语动词 + 其他部分,如：
It is how much they need to learn that students realize at this time how much they need to learn and how little 学生们在这个时候意识到的正是他们需要学多少.（强调宾语从句）

这里是 it is …… that 的强调句
强调 at this time 在这个时候，学生们才意识到他们要学的还有如此的多，以及他们还剩下如此少的时间。
students realize how much they need to learn and how little time they have to do it.
这整个句子，students 是主语， realize是谓语，后面全部的是宾语从句
how much they need to learn 由疑问词how much引导的宾语从句，
和由how little 引导的宾语从句
how much they need to learn 还原成陈述就是 they need to learn 多少的东西
how little time they have to do it 还原成陈述的就是 they have 多少的时间 to do it