池中的睡莲所遮盖的面积每天扩大一倍，40天正好遮住整个水面，问遮住水面的一半需要（　　）天．

某实验小组欲制取氧化铜并证明氧化铜能加快氯酸钾的分解，进行了如下实验：

（一）制取氧化铜

①称取2gCuSO₄•5H₂O研细后倒入烧杯，加10mL蒸馏水溶解；

②向上述CuSO₄溶液中逐滴加入NaOH溶液，直到不再产生沉淀，然后将所得混合物转移到蒸发皿，加热至沉淀全部变为黑色；

③将步骤②所得混合物过滤、洗涤，晾干后研细备用．

回答下列问题：

（1）上述实验步骤中需要使用玻璃棒的是____ （填实验序号）

（二）证明氧化铜能加快氯酸钾的分解并与二氧化锰的催化效果进行比较

用右图装置进行实验，实验时均以生成25mL气体为准，其它可能影响实验的因素均已忽略，相关数据如下：

回答下列问题：

（2）上述实验中的“待测数据”指____ 

（3）若要证明实验⑤中干燥管内收集的气体是O₂，可待气体收集结束后，用弹簧夹夹住B中乳胶管，拔去干燥管上单孔橡皮塞____ 

（4）为探究CuO在实验⑤中是否起催化作用，需补做如下实验（无需写出具体操作）：

a．____  b．CuO的化学性质有没有改变．

下列各句中，没有语病的一项是（   ）

阅读下面短文，完成已给了首字母的单词，使短文完整、通顺。

     Time passes swiftly and never r____ Our three years of Junior high school life will come to an e____ We'll have to say goodbye to each other—to our best friends and to our beloved teachers. I have all the happy and sad m____ of the three years in my heart.

    Three years ago, three boys came to a school from different places. They were my best friends and I. At that time, we were young and shy of each other. H____, as time went by, we became closer and closer. We studied hard together, played sports together and hung out with each other. When we failed exams, we e____ each other. We faced challenges together, and solved problems together. We s____ happiness and sadness, and grew up together.

    Now, as best friends, we have to face the future separately (分离). Nothing can c____ the fact. I believe that, a____ we may end up in different high schools, our friendship will last.

    I have one w____ for my friends. I hope they will get good grades in the high school e____ exams.

3个9相加得____，再加上2个9得____。