题目

碳酸钠俗称纯碱，是一种重要的化工原料，下列用复分解反应的方法制取碳酸钠合理的是（ ）A.2Na+H2CO3=Na2CO3+H2B.2NaOH+CaCO3=Na2CO3+Ca(OH)2C.2NaOH+H2CO3=Na2CO3+2H2OD.2NaNO3+K2CO3=2KNO3+Na2CO3 答案：【答案】C【解析】复分解反应是由两种化合物互相交换成分，生成另外两种化合物的反应。A、钠的活动性很强，能与水反应，故A不正确； B、碳酸钙不溶于水，氢氧化钠不与碳酸钙反应，故B不正确； C、该反应能用复分解反应的方法制取碳酸钠，故C正确； D、该反应没有气体、沉淀和水生成，该反应The other night, I had to go to a meeting, which lasted past my daughter's bedtime. I 1 home and was brushing my teeth when I 2 , and there on the bathroom mirror was a note in the 3 of a heart . It said, "Hi, Mom! I Love You. Laurel. " 4 , I cut a heart out of a piece of paper, and taped a(n) 5 next to hers , saying , "I Love You , too , Laurel .  Love, Mom," which she 6 the next morning. Our family has 7 that by integrating writing into our 8 activities, we become more thoughtful of each other. Meanwhile, our daughter is learning to enjoy writing and be- coming a( n) 9 writer. While teaching in a primary school, I 10  how influential parents can be as children learn to write. 11 when our daughter first began to scribble (乱涂) , I became 12 by her work . I offered praise for her 13, for I found that scribbling is far more complex and important than I had 14 . It was obvious that her scribbles, 15 being lovely art objects, showed a lot about her 16 of the world of writing. Gradually, our family began writing a great deal. I sensed that writing helped Laurel learn 17 to read. As a matter of fact, by 18 my own child and her friends and by reading professional books, I became more and more 19 about how writing develops and how 20 can help children become eager writers. 1．A．left                      B．returned              C．missed               D．headed 2．A．turned up             B．turned down       C．looked up           D．looked on 3．A．size                      B．shade                 C．model                 D．shape 4．A．Immediately          B．Suddenly            C．Finally                D．Directly 5．A．picture                 B．article                 C．note                   D．page 6     A．felt                     B．wrote                 C．read                   D．heard 20080520   7．A．found                   B．imagined             C．dreamed             D．doubted 8．A．relative                 B．useful                 C．daily                   D．personal 9．A．important             B．ordinary              C．fortunate            D．skilled 10．A．learned               B．regarded             C．considered          D．discussed 11．A．Yet                    B．Though              C．But                    D．So 12．A．Disappointed       B．attracted             C．puzzled               D．worried 13．A．effects               B．efforts                C．suggestions         D．methods 14．A．cared                 B．insisted               C．realized               D．proved 15．A．apart from          B．far from             C．instead of           D．rather than 16．A．arguments          B．fear                    C．understanding     D．dislikes 17．A．when                 B．how                   C．what                  D．whether 18．A．noticing              B．discovering         C．checking            D．observing 19．A．particular            B．clear                   C．anxious              D．crazy 20．A．teachers                 B．friends            C．books                    D．parents