好听

pleasant to hear; nice to listen to; pleasant-sounding; melodious; musical; sweet-sounding; euphonious

简单

simple; plain; brief; uncomplicated; straightforward; easy; elementary; undemanding; simply; plainly; simplicity; easiness; simplify; make simple; keep it simple; make it simple; tout court; easy as pie

儿歌

nursery rhyme; children's song; rhyme