used to say yes or to give someone permission to do something

"Can you help me?" "Of course." “你能帮帮我吗？”“当然可以。”

"May I look at your newspaper?" "Of course you can." “我能看看你的报纸吗？”“当然可以。”

"Have you written your English essay yet?" "Of course, I finished it last week." “你的英语论文写了吗？”“当然了，我上周就写完了。”

used to show that what you are saying is obvious or already known

The Second World War ended, of course, in 1945. 第二次世界大战当然是结束于1945年。

used to show that a situation or a piece of information is not surprising

We arrived at the restaurant 30 minutes late so, of course, our reservation had been cancelled. 我们到餐馆晚了30分钟，所以，预订自然就被取消了。