题目

某人不色盲，其父母、祖父母、外祖父母色觉都正常，但弟弟是色盲，那么色盲基因传递的过程是 A.祖父→父亲→弟弟 B.祖母→父亲→弟弟 C.外祖父→母亲→弟弟 D.外祖母→母亲→弟弟 答案：D--I'd like to invite you to dinner this Saturday, Mr Smith. --________. [　　] A. Oh, no. Let's not B. I'd rather stay at home C. I'm very sorry, but I have other plans D. Oh, no. That'll be too much trouble