【正确答案】 B

【答案解析】[解析] 画线词组now and then为副词词组，意为“时而，偶尔”。A项always意为“经常”，例：They"re always arguing.他们经常争论不体。B项occasionally意为“时而；偶尔”，例：We occasionally meet for a drink after work.我们下班后偶尔相聚小酌一番。C项constantly意为“不断地”，例：She is constantly changing her mind.她老是改变主意。D项regularly意为“经常地；定时地”，例：We do meet now and then, but not regularly.我们确实偶尔见面，但并不经常见面。故选B。