doubtful about

• 对 ... 有怀疑； 对 ... 不能确定

doubtful about的用法和样例：

例句

1. I am doubtful about the value of your proposal.
   我怀疑你的提议是否有价值。
2. I am doubtful about the propriety of granting such a request.
   我怀疑答应这项要求是否合适。
3. I'm rather doubtful about his integrity.
   我对这事的忠诚颇有怀疑。
4. Because of a long drought, the farmers are doubtful about the prospect of a good yield.
   因为长时间的干旱，农民们对于好收成的前景是怀疑的。