If the future or success of someone or something is in doubt, it is unlikely to continue or to be successful.

The future of the stadium is in doubt because of a lack of money. 由于缺少资金，该体育馆能否建成还不确定。

Their long-term survival remains in doubt because of the twin disasters of habitat loss and climate change.

The outcome of these talks is now in doubt.

Tragically, this generation are inheriting a planet whose viability is in doubt.

Sadly, he's not the only potential team member whose fitness is in doubt.

See also: doubt noun