When riding in rainy conditions, which road surface features become exceptionally slick and require extreme caution, upright posture, and avoidance of heavy braking?

1. Freshly laid coarse asphalt only
2. Dry concrete pavement
3. Gravel run-off escape ramps
4. Painted road markings (thermoplastic paint), metal manhole covers, and tram/railway tracks (路面标线、金属井盖和铁轨)