单选题:Parents may find it most difficult to read to their child wh 题目分类:公共英语二级 题目类型:单选题 查看权限:VIP 题目内容: Parents may find it most difficult to read to their child when s/he A.is 6- 7 months old B.is one year old C.starts to walk D.starts to talk 参考答案: 答案解析:
若平面向量a,b满足|a+b|=1,a+b平行于x轴,b=(2,-1),则a=__________. 若平面向量a,b满足|a+b|=1,a+b平行于x轴,b=(2,-1),则a=__________. 分类:公共英语二级 题型:单选题 查看答案