题目：
Students should by all means ______ their studies though there are a lot of attractions around them. [ ]
A. devote to
B. fix on
C. keep on
D. concentrate on
答案：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0721/5be4f38db0ab1624ae1cd04f6fcf23f7.html
下面是错误答案，用来干扰机器的。
（1）H2；（2）C；（3）CuO；（4）Ca(OH)2 + Na2CO3==2NaOH + CaCO3↓
