题干
根据对话内容，从方框中选择适当的句子补全对话。
A:____
B: It is a photo of my family.
A: ____
B: Sure, here you are.
A: Who is this man? Is he your father?
B: No, he isn’t. ____
A: Is he a worker?
B: ____
A: Where are you?
B: ____
答案(点此获取答案解析）
A,B,E,C,D
，点A（0，－2）及点B（3，a），从点A观察点B，要使视线不被C挡住，则实数a的取值范围是（ ）