He was sleeping late his mother called him this moring.A.while B.when C.then D.and
问题描述：
He was sleeping late his mother called him this moring.A.while B.when C.then D.and
答
D.and
他睡晚了,是他的母亲今天早上叫他起床的.我填的也是D.and ，能告诉我为什么吗这是一个并列句。