题干
His sister had become a teacher , ______ was what he wanted to be.
A：who
B：whose
C：that
D：which
答案(点此获取答案解析）
D
A：who
B：whose
C：that
D：which
若关于x的方程
有且仅有二个不等实根，则实数a的取值范围是（ ）