The teacher told them not to play （not play）in the steet.
He is interested in playing （play）basketball.
The muisc sounds interesting (interest).
第一题【tell sb not to do sth】用不定式
第二题【be interested in doing sth】对...有兴趣用进行时
第三题sound系动词后面用形容词,修饰物用ing形式