The parents were suspicious about their boy's grades, worrying that he had cheated in the final exam.

这对父母对他们儿子的成绩感到怀疑，他们担心他在期末考作弊。

youdao

They were always very suspicious about their neighbours.

他们总是对四邻存有疑心。

《新英汉大辞典》

I am suspicious about his theory.

我对他的理论感到怀疑。

youdao

Why should I be really suspicious about what I see in the screen here?

哪儿不对呢？我为什么要怀疑,屏幕上的答案呢？

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Officials said that there was "nothing suspicious about his intentions" to visit the country.

BBC: Obama says US will pursue plane bomb plotters

Once I became suspicious about the King mask e-mails, I started questioning every e-mail I received.

NPR: Slate's Ad Report Card: Burger King's Buzz Marketing

What's suspicious about some of these arguments is that they have appeared only recently.

CNN: Now It's Her Turn