Experiments have also cast serious doubt on the belief that yawning is triggered by a drop in blood oxygen or a rise in blood carbon dioxide.

对于打哈欠是由血液中的氧气减少或血液中的二氧化碳增加引起的这种观点，一些实验也同样提出了严重的质疑。

youdao

This latest evidence casts serious doubt on his version of events.

最新的证据使人们十分怀疑他对事件的说法。

《牛津词典》

As for the effectiveness of markets, this has surely not been called into serious doubt.

至于市场的有效性，当然还没有遭受严重质疑。

youdao

There may have been several more. People who knew John Slaughter said there was no doubt they were dealing with an extremely serious man -- a man who could be very dangerous.

VOA: special.2010.03.17

But climate change skeptics have seized on the recent theft of thousands of private e-mail messages from computer servers at a British climate research center to cast doubt on whether global warming is as serious as it has been made out to be.

VOA: standard.2009.12.09

Take it, call your mother, and tell her there is serious doubt about you ever becoming a lawyer.

FORBES: The Case Against Law School

There have been seven Nobel Prizes awarded to scholars whose work cast serious doubt on Keynesian economics.

FORBES: Are CBO Estimates Really The Gold Standard Of Accuracy?

Former captain Graham Gooch told BBC Radio Four's Today programme on Monday the Test tour was in "serious doubt".

BBC: England offered new tour schedule