is known to all is that the Diaoyu Islands have belonged to China since ancient times.
She’s having a lot of trouble with the new computer, but she doesn’t know whom to ________.
________ you’ve heard the song, you’ll never forget it.
The mother asked the boy ________ football in the street. It was dangerous.
—I’m going to the States.—How long ________ you ________ there?
Can we ________ the internet when we study?