Environment is very________,but you don’t understand the_______ of it,youalways drop litter everywhere.
There is ______milk in the bottle. Let’s go to buy some.
If you don’t know how to pronounce new words, ____in a dictionary, please. A. look up it B. look it up C. look them up D look up them
She said she had some trouble ___________ her homework.
Do you enjoy __________ on the Internet?
He learns English by ____________ English songs.