Except

except , unless : These words are not synonymous. Avoid such locutions as “You will not enjoy it except you earn it.” Say rather, “You will not enjoy it unless you earn it.”

Except Unless , are often used confusedly. “I shall go except I am ill.” Say “unless I am ill.” “I saw them all unless two or three.” Say “except two or three.” The correct usage is easily learned by observing that except  should be used as a preposition, unless  as a conjunction.