线路上部建筑包括哪些？
参考答案：
包括与列车直接接触的钢轨、轨枕、道床、道岔和防爬设备、联接零件等部件。
用所给词的适当形式填空。
1. I like swimming very much. Let's _____ (swim) after school.
2. Keep quiet, please. I _____ (read) a newspaper.
3. Helen enjoys _____ (sing) in Chinese.
4. He _____ (buy) the morning paper this morning.
5. How many _____ (visit) are there on the bus?
6. You'll become a _____ (win)! Congratulations!
7. Thanks for _____ (send) me home.
8. _____ (fortunately), he died last month.
9. The old man _____ (tell) two stories last night.
10. I usually have lunch at school. But yesterday I _____ (have) it at home.
有一种固体混合物，可能由CuSO4、CaCO3、Na2CO3、BaCl2、NaCl中的一种或几种组成，现取该混合物进行如下实验：①将固体温合物溶于水中，搅拌后完全溶解得到无色溶液．②往此溶液滴加盐酸，产生一种能使澄清石灰水变浑浊的无色无味气体．据此，试推断：该固体混合物中一定有______，不能肯定是否存在的是______．
