为什么选if不选because

题目

为什么选if不选because
She didn't go to the party last night,_____ she had to finish her term paper.
选项是 if,though,till,because

答案

楼主 就应该选Because 您在看看
根据句意 昨晚她没去参加晚会 因为必须完成学期论文不应该是if