I have twin girls,who are in good health,have no problem preventing them from speaking,. they speak very few words although they understand every word I say... how can I help them?

1) Get them checked by your doctor.
2) Get him to refer them to a specialist.
3) You have an advantage already because you have twins, they should be talking to each other.
4) If possible get them enrolled in pre school,
Mixing with other children is very good.

Consult ent

If there is no prob, it won't be by god's grace make them to sing along any songs,, ask them more questions in the way to make them response...

Get your doctor to refer you to a speech therapist. One of the things she taught me was to reward your child for when they speak what they want. Consequently, "cookie" was used quite a bit, but it got her speaking very well.