We need have more exercise.need 做助动词,have exercise(名词)=exercise(动词) 动词 more 限定词,much,a lot of 的比较级.
We need to exercise more.need 行为动词,后接不定式to exercise .more,副词,more than usual,更多.
we need more eercise.need 行为动词,后接名词.more 限定词,much,a lot of 的比较级.