Learn Turkish: Arabayı tamirciye bırakman lazım. - You need to leave the car with the mechanic.

This uses the necessity structure from this lesson. We take the root bırak (leave), add the verbal noun ending -ma, and the possessive ending -n for "your". Literally, bırakman lazım means "your leaving is necessary".

The English translation says "with the mechanic." Why does Turkish use tamirciye instead of a word for "with"?

The verb bırakmak (to leave) requires the dative case (direction towards) when you specify who or where you are leaving something. You aren't doing an activity together with the mechanic; you are leaving the car to them. We add the buffer -y- and the dative -e to get tamirciye.

Why is the word for car written as arabayı?

Because it is the specific thing being left. It acts as the direct object of the verb bırakmak, so it needs the accusative case. We add the buffer -y- and the suffix -ı to araba to show it means "the car".

Where is the word for "you" in this sentence?

It is hidden in the ending of bırakman (your leaving). You could start the sentence with the pronoun senin (your) for emphasis, making it Senin arabayı tamirciye bırakman lazım, but it is usually dropped because the -n ending already tells us who needs to do the action.