great changes _______ in my hometown since i left here ten y

great changes _______ in my hometown since i left here ten years ago.
a.were happened b.took place c.have taken place d.had happened
when li ming arrived home,he found that his mother ______already ______to hospital.
a,has;been sent b.had;sent c.has;sent d.had;been sent
we ______five english songs by the end of last term.
a.had learned b.learned c.have learned d.will have learned
han mei told me she _______lunch,so she was very hungry.
a.hasn't have b.hadn't had
there are many people downstairs.what do you think _______________?
a.to happen b.happening c.is happened d,has happened