A:
B:
C:
D:
Here is the bulletin board in Class 2. Some of the notes can be seen every day. Here are some notes before a holiday. Please read them and answer the following questions.
①按如图所示的装置连接好仪器;
②检验装置的气密性;
③在A中加入适量的苯和液溴的混合液体,再加入少量铁粉,塞上橡皮塞,打开K1、K2、K3止水夹;
④待烧瓶a中收集满气体后,将导管b的下端插入烧杯D里的水中,挤压预先盛有水的胶头滴管,观察实验现象.
根据汉意写单词。
______,已逐渐成为人们生存发展第一需要和终身受益的财富,甚至决定其一生的命运。( )