Children in hospital usually turn to__________in order to catch up with their school work.

A．comments on three different opinions.
B．favours one of the three opinions.
C．explains an opinion of his own.
D．revises someone else's opinion.

A．sleeping less is good for human development.
B．people ought to be persuaded to sleep less than before.
C．it is incorrect to say that people sleep too little.
D．those who can sleep less should be encouraged.