she must have burnt her midnight oil for the whole week,_____she got very good marks in the exams.
问题描述：
she must have burnt her midnight oil for the whole week,_____she got very good marks in the exams.
A.for B.because C.since D.as 需说明理由,分析各个选项
答
B since 和as应该用在句首,for跟名词可答案是A抱歉，答错！那你知道为什么是这个 吗