sky-writing

n [U] (forming of) legible words in the sky from the smoke-trails of aircraft, usu to advertise sth 飞机放烟组成（的）空中文字（通常为宣传）.

skittishly, skittishness, skittle, skive, skiver, skivvy, Skokie, skua, skulduggery (also skullduggery), skulk, skull, skull and cross-bones, skull-cap, skunk, sky, sky-blue, sky-diver, sky-diving, sky-high, sky-rocket, skylark, skylight, skyline, skyrocket, skyscraper, skywards, slab, slack, slacken, slacker, slackly, slackness, slag, slag-heap, slain, slake, slalom, slam, slander, slanderer,