Wǒ yǒu shì yào gàosù nǐ.
我有事要告诉你。
I have something to tell you.
Notes:
我(wǒ): I
有事(yǒu shì): have something
要(yào): want
告诉(gàosù): to tell
你(nǐ): you
Example:
A: 我有事要告诉你。
Wǒ yǒu shì yào gàosù nǐ.
I have something to tell you.
B: 什么事?
Shénme shì?
What?