It is interesting to visit another country, but there are some problems when we don't know the 1very well.It may be 2 to talk with the people there. We may not know how to use the telephone in the country that we are visiting. We may not know how to buy 3 we need. In a4country we might not know where to eat or what to order in a 5 It is not easy to decide how6to tip (给……小费) waiters or taxi drivers. When we need help, we might not know how to ask for help.It is not pleasant to have an experience7that. 8a short time, however, we learn what to do and what to 9We learn to enjoy life in another country and then we may feel 10 because we have to leave.

圆：x²+y²-4x+6y=0和圆：x²+y²-6x=0交于A,B两点，则AB的垂直平分线的方程是 (    )

已知K_sp（AgCl）=1.56×10^﹣10，K_sp（AgBr）=7.7×10^﹣13，K_sp（Ag₂CrO₄）=9.0×10^﹣12．某溶液中含有Cl^﹣、Br^﹣和CrO₄^2﹣浓度均为0.010mol•L^﹣1，向该溶液中逐滴加入0.010mol•L^﹣1的AgNO₃溶液时，三种阴离子产生沉淀的先后顺序为（　　）