be full of中的be用什么时态？
be full of中的be用一般现在时还是一般过去时？
be full of中的be指什么？
is full of和was full of的区别，什么时候用is full of，什么时候用was full of？
认真体会下例句子，你就应该知道be full of中的be应该用什么时态了：
My bag is often / always / now full of books.
My bag was full of books yesterday.
My bag has been full of books since the day before yesterday.
