表示否定的意思。
doesn't是don't的单三形式，does的否定式。didn't是它的过去式。
注:does是do的第三形式。
造句：
1、A politician who doesn't understand arts and humor can only bring a desert to people.
一个不懂艺术和幽默的政治家，给人们带来的只能是沙漠。
2、It doesn't take much to stir the students to violence.
不用费多大劲就能把学生鼓动起来进行暴力活动。