Aplicația este accesibilă de pe ecrane late

Some fasteners existed before Sundback’s invention, so they were earlier __________.
These early fasteners sometimes opened __________.
Sundback carefully studied their technical __________.
He increased the number of fastening __________.
His improved model used small metal __________.
These parts fitted together __________.
The moving part of a zipper is called the __________.
This part joins or separates two __________ of teeth.