He is sure of his success. = He is sure that he will succeed.
他确信他会成功。(他本人确信)

[跟踪练习]
根据汉语意思,完成下面句子,每空词数不限。
1. 你相信约翰害怕晚上一个人呆在家里吗?
Can you believe that John ______________ at home alone at night?
2. 这个老人买不起城里的新房。
The old man ______________ a new house in the city.
3. 请注意这个单词的发音。
Please ______________ the pronunciation of the word.
                                                                                    湖北  肖步富
Key:
1. is terrified of staying    2. can’t afford to buy      3. pay attention to