Contact us
Choose a category below so we can get back to you as quickly as possible.
60是最小公倍數,60=3*4*5 所以,只能是2,3,4,5 驗證一下,的確倒數相加為77/60
We and our partners use cookies and other technologies to analyze traffic and optimize your experience. View more info and control your cookies settings at any time in our Cookies Policy.