I( was )at school just now
he ( was )at the camp last week
we ( were )students two years ago
they ( were )on the farm a moment ago
yang ling ( was )eleven years old last year
there( was )an apple on the plate yesterday
there ( was )some milk in the fridge on sunday
the mobile phone ( was )on the sofa yesterday evening
有过去具体某一时间的都用过去式.另外注意主语是可数还是不可数,可数是单个还是多个