下列净化水的操作可以降低水的硬度的是（ ）
A．静置
B．吸附
C．过滤
D．蒸馏
A、硬水就是里面含有较多的可溶性钙镁化合物，静置只是沉淀大的颗粒，不能除去可溶性钙镁化合物，故选项错误．
B、吸附只能吸附色素和异味，不能除去可溶性钙镁化合物，故选项错误．
C、过滤只能除去不溶于液体的固体，不能除去可溶性钙镁化合物，故选项错误．
D、蒸馏能使水中可溶性钙镁化合物除去而降低水的硬度，故选项正确．
故选D．
| 短文改错。 文中共有10处语言错误，每句中最多有两处。 错误涉及一个单词的增加、删除或修改。 增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。 删除：把多余的词用斜线（＼）划掉。 修改：在错的词下划一横线，并在该词下面写出修改后的词。 注意：每处错误及其修改仅限一词。只允许修改10处，多者（从第11处起）不计。 | |
| Peter was a small boy. He lived in with his parents in a small house near some hills. People there were both poor. One night it was very dry and windy. When everybody was asleep, Peter sudden heard some noise. It came out from the kitchen. He got up and walking to the kitchen. He found that the wood besides the stove was burning. There was no water tap in the house, but he could not put out the fire. He shouts loudly to wake up everyone in the house. Then she ran out of his house and knocked at the doors of many houses to wake people up. They all left their house quickly. At last the fire was put out the firemen. Many houses were burnt. But nobody was burnt in the fire. _______________________________________________________________________________ |
