Don’t forget to examine the test paper you have just finished_____the possible mistakes in it .

______ with people in the West, people in the East pay more attention to their family.

(2013·青岛一模)All flights ________ owing to the heavy fog, many passengers could do nothing but take trains.

_____ to sunlight for too much time, as the doctors say, will do harm to one’s skin.

Gunpowder is generally believed __________ in ancient China.