As we know, ________ is good exercise and it is necessary for health.A. walk B. walks C. walking
—____ can come in. I’m too busy to see ____. —Ok, I know.
–I won the first prize in English Writing Competition. --_____________.
Turn the radio ______, please! The baby has just fallen asleep.
At the top of the high mountains, there is very _____ oxygen in the air.
Thank you for __________ me to you party.