题干
Usually the students have ________ holiday in summer.
A：a 8-week
B：a 8-weeks
C：an 8-week
D：an 8-weeks
答案(点此获取答案解析）
C
Usually the students have ________ holiday in summer.
A：a 8-week
B：a 8-weeks
C：an 8-week
D：an 8-weeks
存在
，使
；
对任意
。
为假命题，则实数m的取值范围为 （ ）