公交车的座位为什么用硬的

{!-- PGC_VIDEO:{"thumb_height": 360, "thumb_url": "24377000031bda922d959", "vname": "", "vid": "v020166c0000bko465r6936p40nljbig", "thumb_width": 480, "src_thumb_uri": "2b17a00023263d80a8b35", "sp": "toutiao", "update_thumb_type": 1, "vposter": "http://p0.pstatp.com/origin/24377000031bda922d959", "video_size": {"high": {"duration": 60.069, "h": 480, "subjective_score": 0, "w": 640, "file_size": 1937970}, "ultra": {"duration": 60.069, "h": 720, "subjective_score": 0, "w": 960, "file_size": 3559466}, "normal": {"duration": 60.069, "h": 360, "subjective_score": 0, "w": 480, "file_size": 1411788}}, "md5": "4fc9400e94b7e293b87eaf2ff2521a97", "duration": 60.069, "file_sign": "4fc9400e94b7e293b87eaf2ff2521a97", "thumb_uri": "24377000031bda922d959", "vu": "v020166c0000bko465r6936p40nljbig"} --}