"They are not teachers."

Translation: 他们不是老师。

[nikki477251]

Also, in other comments they said if its a "negative" sentence 是 is not needed..

[sea.weed]

Could the people you speak of have been referring to 很? I know that's the case for that character.

[TayoMoore]

What are the rules for he plural vs she plural for they?

[cagprado]

们 indicates it's plural! This applies for both 他 and 她! If the gender is unknown or mixed, use always 他.

[Cheeze189073]

(Sorry if i don't spell the pronounciations right) Ta men is plural and ta is singular.

[luizaurus]

You can't tell if the English sentence is talking about men or women....
I've made plenty of 'mistakes' while translating to Chinese because of this

[Carambar7]

I'm confused, as there is no way to know if the sentence is for plural he or she...

[Sikeryali]

们 (Men) is used to make plurals.

她们 (Tāmen) = They (She plural)

他们 (Tāmen) = They (He plural)

我们 (Wǒmen) = We

你们 (Nǐmen) = You (plural)

[WangYangSo1]

That is correct, and in the same way, when a chinese says "tamen" you have to know from what is spoken if they mean men or women.

[Aralearns]

I exactly typed 他们 不是 老师。 Why are they showing it wrong???

[sea.weed]

That is correct -- I see you put spaces between words though. Unlike English, Chinese is written without spaces between successive characters and words.