Last night Mr. Crook didn’t come back at the usual time. ______, he met some friends and atayed out unitl midnght.
Ugly papers sold on streets are another problem of pollution. Young readers should _____ them.
Both the man and his horse ________ after the long ride.
When you ______ the book please return it to the library on time.
The world is _______ seven continents and four oceans.
It is difficult for you to ______ what will happen in space without gravity.