If someone iswelcometo someone or something, they can have it or do it,especiallybecause it is notwantedby anyoneelse:
可以随便拥有，可以随意做（尤指那些不被别人看重的东西或事）You'rewelcometo it - I can never get it toworkright.你尽管用——我就从没能让它正常运转过。
If theywanttochangetherules, they arewelcometotry.如果他们想改变规则，尽可以试试。