Definition: to not be certain Level: B2
新政策的成功与否仍不确定。
The success of the new policy ___is still ___in ___doubt.
如果你对答案不确定，就向老师请教。
If you ___are ___in ___doubt about the answer, ask your teacher for clarification.
他的资格一度受到质疑，直到他出示了必要的证书。
His qualifications ___were ___in ___doubt until he produced the necessary certificates.
