be doubtful about

• 对 ... 感到疑惑； 怀疑 ...

be doubtful about的用法和样例：

例句

1. Many people have doubts about the new project.
   许多人对这项新工程有怀疑。
2. I'm doubtful whether she's still alive.
   我怀疑她是否还健在。