Everybody should remember it is not _________ to swim in the river alone.
________ city would you like to live in, Beijing, Shanghai or Chongqing?
If prices rise too high, the government has to do something ______ it.
— How long have you _______ this book?— About ten days. I _______ it last month.
— When will the second class begin?— _________ two minutes.
— I’m sorry I can’t find the library book anywhere.— So…I’m afraid you have to _________ it.