The number of entries is based on the VO's discretion, not of your choice. If the VO doesn't see special needs in your application (from the VO's point of viewm not yours), the Chinese passport holder will get 3 - 6 months visa with 2-entry.
If you live near the border, and show you need to cross the border to work in US and come back to Canada everyday then you might get multiple-entry visa up to your I797 valid date. Or you need to travel abroad(outside of North America) frequently, you might also get multiple-entry visa. Again, this is also based on the VO's discretion to issue multiple-entry visa or not.