The research mainly deals with the difficulty the students have ______ their attention pm their study all the time.
Christmas in the western is______ as the Spring Festival in China.
Everybody said it was a perfect marriage; no one had ever known______ couple.
What a wonder! They've finished ______half of the project in such a short time.
To keep a trade______, they would have to sell less and buy more in the following months.
She likes _______ but she doesn’t like _______ now, because there are too many people in the pool.