—Will you go to Mary’s birthday party?—No, ____ invited, I can’t go to it. I’ll be too busy then.
Knowledge from real life isn’t easier to forget than __________ achieved from textbooks.
In our city there are several big public parks __________ many people can go to enjoy the beautiful scenery.
Most of the inhabitants (居民) can’t afford to buy houses of their own, because the price is rising __________.
__________ most efficient way to understand thousands of new words is to gain __________ good knowledge of basic word formation.
—Can you help me with the math problem, Dad? ___________. —OK, let me think it over.