工业上利用氟碳铈矿（主要成分CeCO3F）提取CeCl3的一种工艺流程如下： 请回答下列问题： （1）CeCO3F中，Ce元素的化合价为 。 （2）酸浸过程
把下面的这个长句改写成几个较短的句子，可以改变语序、增删词语，但不得改变原意。 总结是一个组织或个人在工作、学习告一段落后，进行回顾、
Mr Smith has bought a new house in the country, around_______some green trees. A. which is B. it is C. which are D. them are
In 2004, I was 22 years old and had just come back to Brazil after 14 months in England, holding my Cambridge Proficiency certificate. After nervously__1__a short training course, I began to give clas
陈旭麓先生说：“人们多注意1840年的划时代含义，实际上1860年同样是一个重要的年份，就社会观念的新陈代谢来说，它比1840年具有更加明显的标界意
There is no believable evidence for the existence of Bigfoot or to put it another way, there's really quite a lot of evidence, but unfortunately it's of very poor quality. That's a problem for Bigfoot
下列说法是否正确？在( )中用“√”表示正确，用“×”表示错误。 ①可以用铁罐贮运稀硫酸
在水平面上有A、B两物体，通过一根跨过滑轮的不可伸长的轻绳相连，现A物体以vA的速度向右匀速运动，当绳被拉成与水平面夹角分别为α、β时（如图3
，其中
． 
解析: