题目

The King family ______ a visit _____ some of their relatives this week. A. is on; toB. is in; of   C. are on; toD. are in; of   答案：Cbe on a visit to去游…，去访问…。一家人应该用复数。若x，y只能取0，1，2，3，4，5，6，7，8，9中的数，且3x-2y=1，则代数式10x+y可以取到 个不同的值，其值为 ．