Last week we called on （ ）选哪个,为什么?

Last week we called on （ ）选哪个,为什么? Last week we called on ____ we worked on the farm last week. last week i called at__ We went on a school trip last week对last week 提问 Last week we——（pick）many apples on the farm适当形式填空 Last week we ------(pick) many apples on the farm. we ____to_____something last week at last week还是 on last week on last week还是in last week The person we talked about ____our school last week.为什么不能选ha The factory is the one （that） we visited last week为什么一定要用tha