They decided to work harder and more effort after their failure.
- A.put in
- B.putted in
- C.put on
- D.be put in
答案
正确答案:A
知识点:实义动词用法

put in more/a lot of effort意思是“投入更多/许多精力”。此题中,and连接的前面短语需保持一致,所以put用原形。故选A。

略
