doubtful [ˈdautful]

adj.

可疑的;不确定的;怀疑的

I am doubtful about what he said.

我对他说的话感到很怀疑。

This is a doubtful battle.

这是一场胜负难测的战争.

近义词synonym

suspicious adj. 多疑的；可疑的

The cause of his death is suspicious.

他的去世原因很可疑。

skeptical adj. 好怀疑的

We were skeptical about the solution.

我们对这个解决方案感到怀疑。

反义词 antonym

credulous adj. 轻信的，

She is a credulous girl.

她是个易受骗的女孩。

undoubting adj. 信任的，不怀疑的

The truth is undoubting.

事实不容怀疑。

词性变化 word-activity

doubtless adv. 无疑地，必然地

He will doubtless arrive by the next train.

他一定会坐下一班火车到达。  

doubt n. 怀疑；

There is no room for doubt.

没有怀疑的余地。   

学习测试---examination

The data comes from the  _____ sources. therefore, we can not use it.

1. doubt; 2. doubtless; 3. undoubting;4. doubtful