Common Mistakes : Every

determiner

.BAD: There was a representative from every countries
.GOOD: There was a representative from every country

.BAD: Every mornings I give him his breakfast
.GOOD: Every morning I give him his breakfast

: every + singular count noun
.I understood every word

.BAD: Every job have its good points
.GOOD: Every job has its good points

: every + noun + singular verb
.Every child was given a red balloon

.BAD: I have to visit the hospital every six week
.GOOD: I have to visit the hospital every six weeks

.every day , every week , BUT , every two days , every six weeks

.BAD: On every Saturday afternoon I play tennis
.GOOD: Every Saturday afternoon I play tennis