"Nobody knows for sure and certain," said Martha.

“没有人确切知道。”玛莎说。

youdao

Conodonts lived in the Cambrian seas, and may have eaten certain types of plankton, but no one knows for sure.

牙形刺生活在寒武纪的海洋中，可能以某种浮游生物为食，不过没人清楚具体情况。

youdao

It is because I am sure the UK would never do so that I am certain the euro is not a sane option for that country.

正是因为我相信英国永远都不会承受这一压力，我才可以肯定，欧元对英国而言并非一个明智选择。

youdao

"Other volunteers took the lead role in making sure that gifts for certain communities stay together and get the process going and making sure that the individuals and volunteers who were there to wrap had a supply of wrapping papers and scissors and tape and everything.

VOA: standard.2009.12.24

He also mocked Trump for telling jurors he never took notes of business meetings and so couldn't say for sure when certain decisions were made and by whom.

WSJ: Talk of lies, pride as Trump case goes to jury

The government would have to set certain standards for it and make sure patients' privacy isn't violated and provide some framework for uniformity.

FORBES: Uwe Reinhardt

The certain answer is that nobody knows for sure.

FORBES: We're Headed To $8 Natural Gas