"上周五開車, 發現engine overheated. 停下檢查, 發現塑料罐coolant 沒了, 加滿後停車狀態下未見coolant滴下."
update:
Thanks to all your help! Just as Ban Zhu said, the thermostat should be replaced. Then coolant has to be filled again if the technician didn't follow SOP. THanks again!