一.作形容詞，意為“確信的；肯定的”

1.be sure of/about對……有把握

I"m sure of/about the test.

我對這次考試很有把握。

2.make sure “確保；確認；查明”，指將某事弄清楚。

I have made sure that he is honest.

我很清楚他很誠實。

be sure對某事或某種情況有把握，常譯為“確信”。

I"m sure that he is honest.

我相信他很誠實。

有時可互換：

Make/Be sure that you have taken your key when you leave the room.

當你離開房間時，要確保你帶了鑰匙。

3.be/make sure to do sth.都表示"一定要做某事"，make sure通常用於祈使句，be sure則不受此限定。

Make sure to come here on time.

一定要準時來這兒。

Be sure to take good care of the baby.

一定要照顧好寶寶。

I"m sure to come here on time.

我一定準時來這兒。

4.be sure of與be sure that可以替換。

I"m sure of success.=I"m sure that I will succeed.

我一定會成功的。

二.作副詞，意為“當然，表示贊同”，相當於of course

- Could you please open the window？

-你能把窗戶開啟嗎？

-Sure.

-當然可以。