题目

.一对夫妇都正常，他们的父母也正常，但妻子的弟弟是色盲.预测他们的儿子患色盲的几率是（  ） A.1                        B.1/2       C.1/4                          D.1/8 答案：C 解析: 妻子的基因型为XBXB或XBXB，只有当基因型为XBXB时，可能出生患病儿子，所以，儿子患色盲的几率应为1/2×1/2＝1/4。--Pity you missed the lecture on nuclear pollution.-- I ___ it, but I was busy preparing for a job interview.A．attendedB．had attendedC．would attendD．would have attended