Travellers coming from outside the US who are exempt from the travel restrictions
transiting passengers (must remain in the secure transit area of a Canadian airport to complete their connection)
Transit to another country by air
You may be permitted to transit through Canada to reach another country.
Prepare for your arrival
make your travel arrangements well in advance if you are transiting through Canada plan your travel so you arrive and depart from the same Canadian airport within 24 hours. Domestic transfers are not permitted make sure your baggage is checked through to a destination outside of Canada connections must occur on the same day at all Canadian airports except Toronto Pearson (YYZ) Overnight connections are not possible at: Montréal-Trudeau (YUL) Calgary International (YYC) Vancouver International (YVR)
During your connection at the Canadian airport
You must remain in the secure transit area to complete your connection. This means that you will not be allowed to collect your baggage, or check-in for your next flight anywhere but at your scheduled gate of departure.
You are exempt from the arrival and Day-10 testing requirements and the mandatory hotel stopover, as long as you remain in the secure transit area to complete your connection within 24 hours.
If you need to leave the airport or the secure transit area due to a flight cancellation or delay, you become subject to mandatory quarantine until your flight departs.
2020 年 8月份 拿的绿卡加ETa 回的中国 ，2021二月份 绿卡加eta 加拿大转机飞的纽约 入境后有工作人员带你转机
回美国 不是联程 海航Air canada 分开买的