He often feels very dull, ________ when he has nothing to do at home.
A.speciallyB.especiallyC.and speciallyD.and especially在线课程B
when引导的是一个时间状语从句，不能与前面主句构成并列句，排除C、D两项。especially常可用在介词短语、状语从句之前，而specially却不能，另外specially意为“专门地，特别地”，侧重目的。故选B项。