( )1.It's difficult for you _____on the top of a very high m

( )1.It's difficult for you _____on the top of a very high mountain.
A.breathing; B.to breathe; C.to breath; D.to be breathing
( )2.--Keep quiet.Dad ________ in the next room.
--Ok.Mum.
A.slept; B.sleeps; C.is sleeping; D.sleep
( )3.The world _______ .Things never stay the same.
A.changes; B.is changing; C.was changing; D.will change
( )4.The dootor told us that the old man was still_____.
A.dangerous; B.a danger; C.in the dauger; D.in danger
( )5.--Where is your mun,Mike?
--She _______ in the kitchen.