题目

 ---Hello! May I speak to Mary? I have _______ to tell her.---Please_______. I’ll go and get her.A. something important; go on          B. important something; hold onC. something important; hold on       D. important something; go on 答案：C   某校开设9门课程供学生选修，其中A，B，C3门课由于上课时间相同，至多选1门，若学校规定每位学生选修4门，则不同选修方案共有种．