covering letter

letter sent with a document, or with goods, etc, typically explaining the contents （随公文、 货物等发出的通常用以说明其内容的）附信.

cousin, cousinly, couture, couturier, cove, coven, covenant, Coventry, cover, cover charge, cover girl, cover note, cover over, cover up, cover-up, coverage, coveralls, covered, covered wagon, covering, coverlet, covert, covertly, covet, covetous, covetously, covetousness, covey, cow, cow shed, cow-pat, coward, cowardice, cowardly, cowbell, cowboy, cowcatcher, cower, cowgirl, cowhand,