【单选题】日常用的电池为锌锰干电池,其电极分别为碳棒和锌壳,以糊状NH 4 Cl作电解质(其中加入MnO 2 氧化吸收H 2 ),电极反应式为:Zn-2e - ═Zn 2+ ;2NH 4 + +2e - ═2NH 3 +H 2 .根据叙述试判断下列说法中正确的是( )
B.
锌锰干电池工作时,电子由碳极经外电路流向Zn极
C.
锌锰干电池长时间连续使用时内装糊状物会流出腐蚀电器
D.
锌锰干电池能将化学能转化为电能和将电能转化为化学能
【简答题】某市政工程公司承包垃圾转运站的停车场水泥混凝土面层工程施工项目。设计为混凝土板厚 24cm ,双层钢筋网片采用普通硅酸盐水泥.施土时日平均气温为 20 ℃ 。因考虑商品混凝土站距离较远,项目部采用现场自拌混凝土。 1 为便于振捣混凝土选择坍落度为 3 - 4cm ,水灰比为0.52 ,水泥用量为 320kg/m3. 2 为加快搅拌速度,每盘使用水泥二袋(100 kg) ,砂、石料使用固定专用车.按...
【单选题】A(an) ______ is a word formed of the initial letter of several words.
【单选题】Why is an initial letter very important? Please select the best answer.
A.
It is important because a successful initial letter will leave a good impression with other.
B.
It is important because it has some promotions.
C.
It is important because the buyer intends to purchase products with a proper price.
D.
It is important because the seller would like to market their products.
【多选题】The basic structure of drafting an initial letter includes:
B.
Introducing how you get the information
【简答题】Charter vessels can be classified into three types: v 1 charter , t 2 charter and d 3 charter or b 4 charter. (When you write the answer, please write the complete word without omitting the initi...
【多选题】The basic structure of drafting an initial letter includes:
A.
Introducing how you get the information
【多选题】The basic structure of drafting an initial letter includes:
B.
Introducing how you get the information
【简答题】Fill in the blanks with words whose meanings are similar to the underlined words. The initial letter of the words is given .(31-40) to walk aimlessly d