—______ do they get a present for their mother?—Because it’s their mother’s birthday.
—What colour is _______ orange ? —It's____ orange .
---Would you like me to take you to the new park? ---__________. I’ve been there once.
It is said that the meeting _______ for a week.
--I hear this kind of CD-ROM is very popular. --Let’s buy one before it ____________.
This problem is ______ difficult __________.