1 . It is not surprising that young people are likely________(burst) out, particularly when there are reasons to do so.

2 . I fell for their trick, so all the naughty boys ________(大笑起来) at me. （根据汉语提示完成句子）

3 . Upon hearing the funny story, everybody ___________(爆发) into laughter. (根据汉语提示单词拼写)

4 . Hospital staff ______(爆发)into cheers after doctors completed a 20-hour operation to have separated one-year-old twins at the head. （根据汉语意思填空）