doubt/ daut /

1.noun [c/u] 
(uncertainty) 怀疑

2.vt.[+person] 
(disbelieve) 怀疑

3.vt.[+person's word] 
不信

4.vt.
(mistrust,suspect) 怀疑

without (a) doubt
无疑地
to be in doubt
不确定
beyond doubt
毫无疑问地
no doubt
无疑地
to doubt if {or} whether...
拿不准是否…
I doubt it (very much)
我(很)怀疑
I don't doubt that...
我毫不怀疑…