If someone tells you there will be a meeting at 3pm, you want to say I know in Chinese. Here we use the word: 我知道了(wǒ zhīdào le). It means thank you for telling me this, I know. Let's look at the sentence more carefully.
我(wǒ):I
知道(zhīdào):to know
了(le):particle word
If someone tells you something you've already know, you want to say I knew it in Chinese. Chinese people will say: 我知道(wǒ zhīdào). This sentence means I've already known this so you don't need to tell me. For example, Mum said to her son: don't forget your bag. And her son replied: Wǒ zhīdào. The reply means I knew, and you're so annoying. Depending your tone, it could be an impolite reply. Let's look at it carefully.
我(wǒ):I
知道(zhīdào):to know
Exercise:
1. Your manager tells you to attend a meeting. What will you reply?
2. "Hi, Anna, please bring me a cup of coffee. Thank you!" What would you say?
3. "don't touch that bottom!" And you will reply......