Although you may meet some difficuIties,you should never .
The houses of the rich are generally larger than _______ of the poor.
When the teacher came in, he saw some boys _______ behind Daniel, _______ the computer games.
It _______ long ______ we know the result of the experiment.
--- Would you please give him the paper the moment he _______? --- No problem.
---Teenagers are sometimes made _________ ______ they are not_________.--- I agree.