Question

I can not tell whether Mary is fat or thin at present,     I have not seen her for a long time.

A.and B.but C.so D.for

Answer

D

【解析】

句意:我现在分不清玛丽是胖是瘦，因为我好久没见到她了。

考查并列连词。and和，又表示并列；but但是，表示转折;so因此，表示递进；for因为，表示原因。根据空前I cannot tell whether Mary is fat or thin at present与空后I have not seen her for a long time后句是前句的原因，要用for连接两个句子，故选D。