怀疑。即可以是动词，也可以是名词。
Whether he will continue to be successful in future is open to doubt.
他今后能否继续获得成功值得怀疑。
There seems no reason to doubt her story.
似乎没有理由怀疑她所说的话。
The success of the system is not in doubt.
这种制度的成功确定无疑。
There is some doubt about the best way to do it.
这件事怎么做才是最佳办法有点吃不准。
