A finite basis of identities is constructed for the semigroup of all r
ank 1 n x n matrices over the field. It is worthy to notice that every
semigroup of all rank r, r > 1, n x n matrices over a finite field ha
s no finite basis of identities. Let G be an arbitrary variety of grou
ps with a finite basis of identities. A finite basis of identities is
constructed for the variety generated by all completely 0-simple semig
roups over G-groups.