YYZ-SIN, PVG-YYZ for $387 (stops in SFO or ORD)
NYC-SIN, PVG-NYC for $454 (stops in SFO on outbound, non-stop on return)
SFO-SIN, PVG-SFO for $510 nonstop
Some dates that seem to work:
Feb 20 to Mar 6
Feb 27 to Mar 13
Mar 6 to Mar 19
Mar 13 to Mar 27
Mar 20 to Apr 3
Mar 27 to Apr 10
Apr 24 to May 8
May 1 to May 15