注意：有拼寫錯誤。如Carefullness 為 Carefulness 之筆誤；carefull 為 careful 之筆誤。下次提交前請先校對一下。　　

Carefulness is necessary. 名詞作主語，把 carefulness 視為一種品質，意指 the quality of being careful and painstaking。　　

To be careful is necessary. 用不定式作主語，強調動作，且暗示指某次特定的情況。　　

Being careful is necessary. 用動名詞作主語，與不定式作主語相比，更強調一般情況（即通常如此）。　　

又如：　　

Everyone needs love. 人人都需要愛（或愛情）。　　

Everyone needs to be loved. 人人都需要有人愛。（不定式的動作意味很強）