As is known to all language learners, the newly learnt words will soon be forgotten unless ______ used in everyday communication.

The airline stewardess (空姐) said to passengers on ______ with a beautiful smile, “welcome _________!”

 The cousins are alike in age，but ________ they are as different as day and night.

 The problem is not _______so easy as you think. It’s far from being settled.

I sincerely regret that I have hurt your feelings, but I didn’t do it ______.