[译] 惟恐父亲生气，他不得不忍住笑。
[误] For fear that his father should become angry he had to refrain to laugh.

[正] For fear that his father should become angry he had to refrain from laughing.
[注] 表示“忍住做某事”，应该说 refrain from doing sth., 在 refrain 后不能跟动词不定式。