【题目】Where have you been all these days? We are very ______ about your safety.
A.interested
B.frightened
C.surprised
D.concerned

【答案】D
【解析】A.interested 感兴趣的；B.frightened害怕的；C.surprised吃惊的；D.concerned挂念的，构成be concerned about关心、挂念；句意：这几天你去了哪儿？我们非常担心你的安全。根据句意，故选D。