shell

n.外壳，甲；炮弹

sheep-dog, sheep-fold, sheepish, sheepishly, sheepishness, sheepskin, sheer, sheet, sheet lightning, sheet music, sheeting, sheikh (also sheik), sheikhdom (also sheikdom), sheila, shekel, sheldrake, shelduck, shelf, shelf-life, shelf-mark, shell bean, shell-shock, shell-shocked, shellac, shellacking, shellfish, shelter, sheltered, shelve, shelves, shelving, shemozzle, shenanigans, shepherd, shepherd's pie (also cottage pie), shepherdess, Sheraton, sherbet, sherd, sheriff,