某溶液中含有Cl^﹣、CO₃^2﹣、HCO₃^﹣等3种阴离子，如果只取一次该溶液就能够分别将3种阴离子依次检验出来，下列实验操作顺序正确的是（　　）

①滴加Ca（NO₃）₂溶液；②过滤；③滴加AgNO₃溶液；④滴加HNO₃溶液．

    Yesterday was Sunday. Tom was at home. He got up at six o’clock in the morning. He had rice for breakfast. At eight he helped his mother do the housework. At nine he watched TV with his father. He cooked fish for lunch. At four in the afternoon he washed his clothes. He went to bed at ten in the evening.

    — Last month.

如图，要修建一条公路，从A村沿北偏东75°方向到B村，从B村沿北偏西25°方向到C村．若要保持公路CE与AB的方向一致，则∠ECB的度数为（   ）