It's difficult to contradict someone politely.
彬彬有礼地驳斥别人是难以做到的。
contradiction n. 反驳,矛盾
Your statements today are in contradiction with what you said yesterday.
你今天的声明与你昨天所说的话相互矛盾。
contradictory adj. 反驳的,反对的
contradictive adj. 抵触的,反对的
contrast n/ vt. 对比,对照
in contrast 相反
Teachers can know the development of students through in-class and
after-class communication. In contrast, Internet has no emotions. It can
not communicate with students.