surface mail

letters, etc carried by road, rail or sea, not by air 陆路邮件, 水路邮件（别於航空邮件）.

suppurate, suppuration, supra-, supremacist, supremacy, supreme, supremely, Supt, surcharge, surd, sure, sure-fire, sure-footed, sure-footedly, sure-footedness, surely, sureness, surety, surf, surface, surface tension, surface-to-air, surfboard, surfeit, surfer, surge, surgeon, surgery, surgical, surgically, surliness, surly, surmise, surmount, surmountable, surname, surnamed, surpass, surpassing, surpassingly,