So absorbed _____ in the experiment that he didn’teven notice it was already over 12 o’clock.

No one can walk the wire in the air without a bit of fear unless ___ very young.

You have to believe in yourself. Self-confidence is_____ to success.

there has been burglary in yourhouse, you should put_____round it before the police arrive to investigate thecase

Please don’t throw paper on the ground. —________.