告发的英文：
blow the gab
blow the gaff
blow the whistle on
delate
delation
denounce
denunciation
eat cheese
grass on
indict sb. for
inform
inform against
inform on
lodge information against
peach
prosecute
split on
tell on
tell tales

The class had an agreement not to sneak on each other to the teacher.
全班学生达成协议，不向教师互相告发。

Give secret information (esp to the police about a partner or accomplice in crime); become an informer.
告密（尤指向警方告发同伙或同谋）；充当告密者

He intends to bring suit against them for misrepresenting the merchandise they sold him.
他打算告发他们把货物卖给他时作虚伪不实的吹嘘。

They decided to inform against him.
他们决定告发他。

Don't split on me.
可不要告发我。

Denunciation to the police
向警方告发

An informer denounced him to the police
检举人已向警方告发他

The class had an agreement not to sneak on each other to the teacher
全班学生达成协议,不向教师互相告发。

Somebody denounced him to the military police as a spy.
有人向宪兵队告发他为间谍。

An informer denounced him to the police(as a terrorist).
检举人已向警方告发他(是恐怖分子).