A ghost indeed! I've never heard anything so silly.

真是见鬼！我可从没听说过这样无聊的事。

《牛津词典》

If you've never done this, it may very well sound silly to you.

如果你不能按照我说的做的话，那么看起来它对你将会是那么的愚蠢。

youdao

I never told Greg about what happened, which occasionally makes me feel guilty, but I chalk my cheating up to being young and silly.

我把所发生的一切告诉了格雷格，现在想起来还时常让我觉得内疚，我把我的撒谎行为归咎于我的年轻和愚蠢。

youdao

Expecting a stock to rise because you own it is as silly a notion as believing that we will never have another recession.

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It's silly, the way we've been brought up about the Germans, because I would never think of coming here if it wasn't for the football.

BBC: NEWS | UK | Frankfurt awaiting England fans

And the girls, three of them university students, are so silly: dreaming non-stop of love and marriage, practising astrology, obsessed by the men they never, or hardly ever, are allowed to see but with whom they chirp like crickets throughout the night on their mobile phones.

ECONOMIST: Saudi fiction