问题补充:
Never protecting our earth. It is the only nice planet for us to live on.
A. leave for
B. learn about
C. give up
D. look up
答案:
A. leave for
B. learn about
(答案→)C. give up
D. look up
解析:句意:不要放弃保护我们的地球。对于我们来说只有一个星球可以居住。leave for 离开去某地;learn about 了解;give up 放弃;look up 查找。根据句意可知,这里让我们不要停止保护地球。give up doing sth. 放弃做某事。故选C。