题干
If we don't study hard, we will in our class.
A：take the lead
B：fall behind
C：be the first
D：be successful
答案(点此获取答案解析）
B
If we don't study hard, we will in our class.
A：take the lead
B：fall behind
C：be the first
D：be successful
3Zn(OH)2+2Fe(OH)3+4KOH