we have good reason to believe that 我们有充分的理由相信
we have good reasons to believe that 我们有理由相信
例句：
We have good reason to believe that he is a good comrade.
我们有理由相信：他是个好同志.
They have good reasons to believe this at the turning point of a new century.
人们对考试持有碍截然相反的两种观点.
加不加复数s,内容明显不一样的!