If you are unable / unwilling to use a VPN to use FB/Twitter, or can't borrow someone's vpn to do so, I can flag a Rep to speak to you privately about some other option.

Hi thanks very much for your reply. Is there any other option to do that? Can I send an email? I do not have vpn and have no idea how to use that. 

No email. But a rep can private message you here. 

Let me flag a rep for you 

Which device are you using? Can you download any apps? If so, you can get an app that can make or receive calls, such as Fongo, and schedule a callback to that number instead. 

I am using Android OnePlus. I am going to try Fongo. Thanks a lot. 

If fongo mobile doesnt work (who knows with the "great firewall" ) - the TextNow app is another worthy alternative, with free calling to Canada / USA. Hopefully one of them work for you.

Another thought to consider... If you like your number and want to keep it for future use when you return to Canada, you could port it out to a parking service like NumberBarn or voip service like Voip.MS... though that could be a complicated if you cant receive the port out verification text in China.. 

Thanks a lot for your detailed suggestion.