Once______ a difficult and even dangerous place______,Vietnam is now a friendly destination that welcomes visitors from all over the world.
. If I can help ____, I don’t like working late into the night.
. ---Why not open the windows to let _____cool air in? ---I’d rather you didn’t. ________air in out town is terribly polluted.
. .----Are my clothes too casual? ----No. You can go ____you are.
. How ___I help them to understand when they won’t listen to me?
. .In summer, food will go bad if________in room temperature.