All lights______after the students left the classroom.
—? —They are reading books. A、What do they do B、What did they do C、What are they doing
His job is funkind of dangerous. A、but B、or C、and
---I haven't seen Jack for three days. Is he ill? ---_______. His mother told me that he was in hospital.
--- How _______ is it from Xi'an to Dunhuang? --- It's less than 3 _______ flight.
--- When did your parents _______? --- They _______ for 20 years.