If I don't send a picture, he will smell a rat.

如果我不寄张照片，他会起疑心。

《柯林斯英汉双解大词典》

I smell a rat.

我觉得事情不妙。

youdao

The repeat patterns in the smoke made lots of people smell a rat and it turned out that Hajj had even copied some of the buildings.

烟雾中重复的样式让很多人感到可疑，结果证实，哈吉甚至复制了其中的一些建筑物。

youdao

Ms.Gardiner said the delay between the arrival of the smell at each nostril could be as little as a half second or less.

VOA: special.2010.08.03

That which we call a rose by any other word would smell as sweet. So Romeo would, were he not Romeo called. Retain that dear perfection which he owes without that title.

我们叫做玫瑰的这一种花要是换了个名字,它的香味还是同样的芬芳，罗密欧要是，换了别的名字，他的可爱的完美,也决不会有丝毫改变。

麻省理工公开课 - 固态化学导论课程节选

You can't smell a radio wave.

你闻不到无线电波。

耶鲁公开课 - 死亡课程节选

Our crook-sniffing equipment is sensitive and we can usually smell a phony a good way off.

FORBES: Dow Jones Interactive

"He also transferred their droppings, so they could smell a bat-friendly area, " Barclay says.

CNN: Architects building dream homes for bats

But I smell a whiff here of stereotyping appearing here about what the Jockey Club is all about.

BBC: Cornelius Lysaght