The phrase "extract them" is correct and can be used in written English.
It means to remove or take something out. Example: The dentist was able to extract them without any pain.
Their quality is largely affected by the weather conditions, the extraction location along the plant and the techniques used to extract them (retting, bleaching, etc).
You had to extract them very carefully.
"That's why the QRF went, to help extract them.
Three different methods are used to extract them.
Ancient artifacts may be plentiful, but that does not excuse the method used to extract them.
Charles Momsen, managed to reach and extract them from the stricken vessel 39 hours later.
When the workers did find bodies, and tried to extract them, the bodies often came apart.
Since every cell of a spider contains the precious silk-producing genes, it's easy to extract them.
To get the stem cells, the scientists must extract them from blastocysts -- early-stage embryos, just a few days old.
Her idea is simply to extract them from the real world and position them like sculptures in the museum.
The anti-abortion movement, meanwhile, is totally opposed to using embryonic stem cells because the scientists have to destroy the embryo in order to extract them.
