These are your English books. But where are ________?

have you been studying English?-For about 2 years. [ ]

My uncle is an experienced teacher. He_____English since 2002.

Most of us still wonder ___________ it is ________ makes those honest peasant workers, without being paid at all, resign themselves to the bosses.

Is Mr Smith still in Shanghai?—Yes，he _______there for two months．