certain adj. 确定的,某一个,无疑的,必然的,可靠的
例句:For certain reasons I will be unable to attend the meeting.
因为某种原因,我不能出席这次会议。
certainly adv. 的确,(口语)当然,行
例句:You certainly did well today.
你今天做得不错。
certainty n. 确定,确实的事情
例句:I can’t say with certainty what project they arc engaged in.
我无法肯定他们在进行什么项目。
ascertain vt. 确定,探知
例句:My purpose is to ascertain whether you are interested or not.
我的目的是要确定你是否感兴趣。
uncertain adj. 无常的,不确定的,不可预测的,靠不住的
例句:I am still uncertain whether Henry will come today.
我仍不能肯定亨利今天是否会来。