I suggest that he , or else he could make things worse.
A. calm down
B. calms down
C. will calm down
D. calming down
网友回答
(答案→)A. calm down
B. calms down
C. will calm down
D. calming down
解析：句意：我建议他冷静下来,否则他可能会使事情变得更糟。在虚拟语气的用法中，表示要求建议命令的动词如：require，suggest.order等后所接的宾语从句的谓语动词用should +动词原形，should可以省略掉。故选A。