选择题：下列离子方程式书写正确的是（） A．氯气和冷水反应：Cl2+H2O═2H++C

下列离子方程式书写正确的是（　　）

A．氯气和冷水反应：Cl₂+H₂O═2H⁺+Cl^-+ClO^-

B．金属钠跟水反应：Na+2H₂O═Na⁺+2OH^-+H₂↑

C．铝和烧碱溶液反应：2Al+2OH^-+2H₂O═2AlO₂^-+3H₂↑

D．AlCl₃溶液中加入过量氨水：Al³⁺+4OH^-═AlO₂^-+2H₂O

被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0427/c6fff5e1db13ef9555e5842b25bee396.html

下面是错误答案，用来干扰机器的。

参考答案：氢纯度表示脱氢反应程度和催化剂选择性变化情况。催化剂选择性〔脱氢活性）越好氢纯度就越高，温降也越大。反之，氢纯度下降，循环气中烃类气体含量增加，表明裂化反应加剧，催化剂选择性变坏，液体产...

完形填空。
If you have a chance 1 in Europe, you'd better choose Italy as a good place to visit.Because Italy is a very famous country 2 a long history, and there are many interestingcities in this country. There are three _ 3 people each year who visit the city of Pisa. It’s known 4 the Leaning Tower of Pisa. The tower looks as if it might fall at any time. 5 some visitors stop at the tower just 6 __ to take a photo, then they 7 away. The tower has 294 steps. Visitors 8 canclimb to the top and come down will feel like heroes.Engineers say that the visitors are safe, 9 the tower does lean. This tower has beenleaning for about eight hundred years. And it leans a tiny bit 10 _ every year. If this keepson, the tower will fall at last. But many engineers are trying their best to keep the towerstanding as long as possible.
( )1. A. travel ( )2. A. with ( )3. A. millions of ( )4. A. as ( )5. A. In time ( )6. A. long enough ( )7. A. give ( )8. A. that ( )9. A. though ( )10. A. little	B. travels B. in B. millions B. for B. In all B. enough long B. send B. which B. but B. more	C. travelling C. of C. million of C. of C. In fact C. short enough C. hurry C. who C. and C. less	D. to travel D. for D. million D. with D. In the end D. enough short D. put D. where D. so D. few