And when,responding to the cheers, he lightly doffed his hat, No stranger in the crowd could doubt 'twas Casey at the bat.

VOA: special.2011.04.04

So, when in doubt, if you're having some weird character issue, odds are you need to escape it in some way.

如果你有拿不准的字符,可能就要用到转义字符了。

哈佛公开课 - 计算机科学课程节选

And in general, what I would say is, when in doubt, use parens. OK.

因此通常上，我会告诉大家的是，当有疑问的时候，请用括号，好。

麻省理工公开课 - 计算机科学及编程导论课程节选

printf Right. When in doubt, let me just use print F for now.

对的，当感到怀疑的，让我现在只用。

哈佛公开课 - 计算机科学课程节选