Question

麻烦大家帮我分析下着几个句子的语法（括号内的），谢谢！

reducing the amount of sleep students get at night has a direct impact on their performance at school during the day.according to classroom teachers,elementary and middle school students who stay up late exhibit more learning and attention problems.this has been shown by BROWN Medical school and Bradley Hospital research.(((In the study ,teachers were not told the amount of sleep students received when compeleting weekly performance reports.)))(((yet they rated the students who had received eight hours or less as having the most trouble recalling all the material.)))

Answer 1

In the study ,teachers were not told the amount of sleep students received when compeleting weekly performance reports.
这句话先是一个被动语态（were not told），然后是一个定语从句（students received修饰sleep，同时省略了that），最后一个时间状语从句的省略形式（when completing）

yet they rated the students who had received eight hours or less as having the most trouble recalling all the material.
这句话先是who引导的定语从句修饰人（students），然后rate as结构表“把……列为……”，最后recalling动词不定式做状语