He put up some signs asking for help

he put up some signs asking for bikes. He also put up some signs asking for old bikes.中的asking for He also put up some signs asking for old bikes.为什么用asking不用t He also put up some signs asking for old bikes.为什么用asking ,用 He also put up some signs asking for old bikes and called up He also put up some signs asking for old bikes解释 He also put up some ___ asking for old bikes and called up a [he put up some signs_(ask)someone for help] ·[he put up some signs_(ask)someone for help] he put up some signs____(ask)for help 现在分词做什么成份?She put up signs asking for singing jobs and also The boy put up some posters——for some old bikes.A,for asking