需要注意噪音（越小越好）和转速（一般越大越好），但这两个存在矛盾，我们选择转速尽量大的情况下，噪音尽量小，这两个不可兼得。In case you are an official representative of J Myles & Co and desire to update your parts of authorized skills for the good thing about your customers, you may amend