可数，复数形式 theories。
theory n.学说;论;说;理论;原理;原则;(未证明的)意见;看法;推测
扩展资料
The theory has been superseded by more recent research.
这一理论已为新近的'研究所取代。
I have this theory that most people prefer being at work to being at home.
依我看，多数人喜欢工作而不愿待在家里。
The comparison shows considerable disagreement between theory and practice.
这一对比表明理论和实践之间有相当大的出入。
I accept his theories, but not without certain qualifications.
我接受他的理论，但并非毫无保留。
And thats where the theory falls down.
这就是该理论的不足之处。
