PCl₃、POCl₃的部分性质如下：

某兴趣小组模拟该工艺设计实验装置如下(某些夹持装置、加热装置已略去) ：

世界气温从低纬度向极地逐渐降低，其主要因素是（    ）

定义在R上的函数$y=f\left(x\right)$，满足$f\left(1-x\right)=f\left(x\right)$，$\left(x-\frac{1}{2}\right)f^{\text{'}}\left(x\right)$，若$x_1<x_2$且$x_1+x_2>1$，则有（   ）．

Last term,Peter was ____ at home.His parents were doing busines in another city. He felt lonely,so he often turned on the computer and played computer ____. However, sitting in front of the computer for a long time is ____ for him. And he spent little time on his study.He failed his exams.Luckily,his parents ____ his problem in time.They decided to come back home.Peter studies hard now.So far,he has made progress in his study.He ____ he can catch up with his classmates soon.