题干
I want to explain _______ that prevented me doing it on time.
A：what was it
B：what it wa
C：why was it
D：why it wa
答案(点此获取答案解析）
B
A：what was it
B：what it wa
C：why was it
D：why it wa
在区间 
单调递增，则k的取值范围是（ ）