He had hardly reached home an unexpected guest came to visit him.
A. then
B. when
C. the moment
D. than
网友回答
A. then
(答案→)B. when
C. the moment
D. than
解析：考查固定句型：Hardly…when…,一…就…,A项then不是连词，C项the moment不和hardly搭配，D项than和no sooner搭配，句意：他一到家，一个不速之客就来拜访他。选B。