After the trainer was sure that the whale could look after itself, he _______ it into the sea.

(2014·北京四中期中)The children________very well last night and the audience were attracted by their play.

 In some developed countries, larger population is ______________ in their big cities.

When the young man was shown the evidence, he _______ and told everything he had done to the police. 

Some passengers were ______ in the traffic accident and taken to the nearest hospital.