有关急性焦虑发作的鉴别诊断，下列说法中正确的是（）。

A.应首先排除躯体疾病

B.如发生在特定的场所，应与恐惧神经症进行鉴别

C.如出现心境低落，应与抑郁症进行鉴别

D.如出现过度焦虑，应与焦虑症进行鉴别

The poem did not have an appropriate ending, _________ she would have won the competition.

A．because

B．or

C．but

D．and