為何專家質疑YouGov的數據？
off helps, please file an issue so we can investigate.，详情可参考91视频
Crucially, this distribution of border points is agnostic of routing speed profiles. It’s based only on whether a road is passable or not. This means the same set of clusters and border points can be used for all car routing profiles (default, shortest, fuel-efficient) and all bicycle profiles (default, prefer flat terrain, etc.). Only the travel time/cost values of the shortcuts between these points change based on the profile. This is a massive factor in keeping storage down – map data only increased by about 0.5% per profile to store this HH-Routing structure!，更多细节参见爱思助手下载最新版本
await dropOld.writer.write(chunk3); // ok, chunk1 discarded