【简答题】现一块铜合金,可能是黄铜(铜、锌合金)、青铜(铜、锡合金)、白铜[铜、镍(Ni)合金]中的一种,现欲测定其组成. [查阅资料]Ⅰ.锌、锡、镍皆能与稀硫酸发生置换反应,生成+2价的金属离子; Ⅱ.相对原子质量Zn-65,Sn-119,Ni-59. [实验步骤及数据]取5g合金粉碎后放入烧杯中,将20g15%稀H 2 SO 4 分四次加入烧杯中充分反应后,测定剩余固体质量数据记录如下: 次数 1 2 ...
【单选题】下列不属于塑料模具结构零件的作用的是( )?
【单选题】函数 上不满足罗尔定理的条件,是因为 ( )
【单选题】变压器副边所带的负载增加时,副边的电压会 ,原边的电流会 。
【单选题】听力原文:M: Finally I got the chance to put on my new suit tonight. I've got to leave a good impression with your family. W: Come on, it's merely a family reunion. So jeans and T-shirts are just fine. Q: ...
A.
She would like to see the man in formal dress.
B.
She believes the man's suit is appropriate for this occasion.
C.
The man could dress casually.
D.
Suit and tie are recommended for tonight's reunion.
【单选题】听力原文: M: Finally I’ve got the chance to put on my new suit tonight. I hope to make a good impression on your family. W: Come on, it’s only a family reunion. So jeans and T- shirts are just fine. Q: Wh...
A.
The man has left a good impression on her family.
B.
The man’s jeans and T-shirts are stylish.
C.
The man should buy himself a new suit.
D.
The man can dress casually for the occasion.