Mandarin is a relatively simple language in that it does not have verb conjugations. The same form of verbs can be used for all tenses.
Negatives are also quite easily formed by simply placing the particle 不 (bù) in front of the verb. Bù can be used for all verbs except 有 (yǒu - to have), which uses 沒 (méi) for its negative form.
Méi is also used for negating Functive Verbs (action verbs) when talking about completed actions. In this situation, méi is a short form for méi yǒu and either form can be used.
Examples of Mandarin Negatives
Wǒ bú yào.
I don’t want (it).
我不要。
Tā hái méi lái.
He hasn’t come yet.
他還沒來。
Wǒ míngtiān bù qù xuéxiào.
I won’t be going to school tomorrow.
我明天不去學校。