题目

The class of eighth grade at a Los Angeles middle school tap their rulers and nod their heads to the rhythm of the rap video shown on a screen. Their algebra teacher, LaMar Queen, uses rhyme to help them memorize seemingly difficult items to improve their grades. Queen, 26, is now known at Los Angeles Academy Middle School as the rap teacher, but his fame has spread beyond the 2，200­student school in this neighborhood. He's won a national award and shown teachers and parents how to use rap to teach children.“Math is a bad word for many students, but if we put it in a form that ki已知直线（a，b是非零常数）与圆x2+y2=100有公共点，且公共点的横坐标和纵坐标均为整数，那么这样的直线共有 [     ]A.60条B.66条C.72条D.78条