— _____ you were so late this morning?

— I forgot to set the alarm before going to bed last night. [ ]

A. Why

B. How come

C. How about

D. How

制动液应保持清洁，严防水分、矿物油及杂质污染制动液；使用前必须检查制动液，如有白色沉淀、杂质等，应过滤后再使用。（）