题目

以生石灰(氧化钙)、纯碱等物质为主要原料制取烧碱，试写出其中两个关键的化学方程式： (1)                                     (2)                                         答案：CaO+H2O==Ca(OH)2  Ca(OH)2 + Na2CO3==CaCO3↓ + 2NaOHIt is said that the weather will       cold for another three or four days. A．look         B．stay           C．last           D．get