Make up sentences.I was in London yesterdayThey were in Africa last summerMary in Canada last weekMy parents in Russia last weekendBill in America last month

I was in London ( Africa, Canada, Russia, America)  yesterday (last summer, last week, last weekend, last month)
They were in London ( Africa, Canada, Russia, America) yesterday (last summer, last week, last weekend, last month)
Mary  was in London ( Africa, Canada, Russia, America) yesterday (last summer, last week, last weekend, last month)
My parents were in London ( Africa, Canada, Russia, America) yesterday (last summer, last week, last weekend, last month)
Bill was in London ( Africa, Canada, Russia, America) yesterday (last summer, last week, last weekend, last month) 

P.S. Во множественном числе употребляется форма WERE.  В единственном - WAS.
P.S.S. Выделенные курсивом слова ты можешь заменить, если захочешь, на слова, указанные в скобках