阅读测试题。
　　北国风光，千里冰封，万里雪飘。望长城内外，惟余莽莽；大河上下，顿失滔滔。山舞银蛇，原驰蜡象，欲与天公试比高。须晴日，看红妆素裹，分外妖烧。
　　江山如此多娇，引无数英雄竞折腰；惜秦皇汉武，略输文采，唐宗宋祖，稍逊风骚。一代天骄，成吉思汗，只识弯弓射大雕。俱往矣，数风流人物，还看今朝。

    There are many different ways to travel to Paris from London. One of the quickest and most popular ways is by train. From Waterloo Railway station, you can travel all the way to Paris. The journey takes about three hours. The train, called the Eurostar, is very modern, and the seats are comfortable.
    You can also travel to France by ship. First, you go to Dover, on the coast (海岸), by bus from London. The bus stops at the Ferry Terminal Seven in Dover. You can buy your tickets there. People who travel by car can drive on to the ferry (渡轮), too.
Another way to travel to Paris is by plane. There are several airports with international flights to Paris and other cities in France. You can travel to London Airport by bus or underground. Some people even go by taxi but this is a very expensive way to travel!

（1）加入HNO₃酸化的Ba（NO₃）₂溶液→白色沉淀→判断一定有SO₄^2﹣，是否正确 ____，理由是 ____　．

（2）加入HCl酸化的BaCl₂溶液→白色沉淀→判断一定有SO₄^2﹣，是否正确 ____理由 ____

（3）加入Ba（NO₃）₂溶液→白色沉淀→再加HCl→沉淀不溶解→判断一定有SO₄^2﹣，是否正确　 ____理由 ____　．

若以上操作都不正确，则正确的操作是：先加入 ____→现象 ____→再加入 ____→现象 ____→判断一定有SO₄^2﹣．