Students _____ remain in their seats until all the papers have been collected.[ ]

You can’t understand the meaning ________you read the text.

When winter comes, it is to throw snowballs and have snowball fights.

. There is such an occasion ___________ we know lots of words, but we can’t choose a suitable one to express ourselves.

How many times have you been to China? —In fact, it is the first time I __________ here