Was it promoted by the other party or introduced by a friend? General training institutions will claim that their pass rate is high. If a friend recommended them, they should have taken the exam there, which is relatively credible.

If you want to choose a school, first look at whether the other party has a physical office address. It's best to make a field trip to see if it's formal, and consult the type of documents that need to be handled face to face, so as not to be useless. If this kind of certificate is true, you can generally check with the issuing authority in official website, and ask the teacher to check the certificate he has handled face to face, so that you will have a good idea.