1、be certain/ be sure
be uncertain about意思是“对……不确定（没把握）”
uncertain的词根是certain,意思是“确信的，有把握的”，常用于以下结构：
(1)be certain(sure) to do sth.“肯定会做……”（表示某事将要发生）。如：
He is certain(sure) to come next Sunday.
(2)be certain(sure) of/ about sth.“确信、有把握”（表示某个人的思想状态）。如：
We are certain/ sure of victory.
(3)名词从句作主语时，一般多用certain.
It is certain that he will come.
2、be different from 与……不同
Your idea is different from mine. 你的想法和我的不同。
对比：make sb./ sth. different from使某人/某物不同于……
Her special accent makes her different from others. 她特殊的口音使她与众不同。
3、be familiar with/be familiar to
be familiar with的主语是有生命的事，意为“某人对人、事熟悉”；be familiar to 的主语是无生命的事物，意为“某人/事为某人所熟悉”，对比:He is very familiar with the names of plants in English.他很熟悉植物的英语名称。Suzhou and Hangzhou are familiar to many foreigners.苏州和杭州为许多外国人所熟悉。
I’m not familiar with European history./European history is not familiar to me.我对欧洲历史不太熟悉。
注意：be familiar with/to 还表示“精通、通晓”
如：French is as familiar to him as English.他对法语就象对英语一样精通。
一句多译
①这些事实是每个学生都熟悉的。
②她精通4种语言。
Key:①These facts are familiar to every schoolboy./Every shoolboy is familiar with these facts.
②She is familiar with four languages./Four languages are familiar to her.
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