— Have you been to the Great Wall? —Perhaps not in my memory. ________, it might have been during my early childhood.

So far, all of the infected people are thought _______ the flu after direct contact with sick birds.

--I’m sorry, I am too busy to help you, but my brother can.I’ve told him to.---______.

As I know, there is ____ car in this neighborhood.

______ is no need for primary students to work at their desks all the long.