_____ about the safety of her son, John’s mother looked upset．

_____ about the safety of her son, John’s mother looked upset．

A.Concerning

B.Concerned

C.To concern

D.Concern

答案及解析： B

解析：

考查固定短语。人担心什么，通常用sb. be concerned about …的结构，该短语是被动语态结构，已经形容词化。所以选B。