Car dealers also have a tough time in bad economy. Therefore，they have to ________ their business model to overcome the difficulties.

--What ____________when I phoned you? ----I_____________and began to have a bath.

When the spaceship was         , I could really feel the high gravity.

— How many teachers are party members in your school?— Party members_________ one fifth of the number of the teachers in our school.

Every pupil has his own potential so it is not proper to _____them ____two kinds．