氯化铁溶液显黄色,其中存在的离子有Fe3+ 和Cl−。在含有Cl−的溶液中加入AgNO3溶液生成白色AgCl沉淀,在含有Fe3+的溶液中加入NaOH溶液生成Fe(OH)3红褐色沉淀。某同学想用实验证明氯化铁溶液的黄色不是Cl―引起的,设计的下列实验无意义的是 ( )
A:观察氯化钠溶液的颜色,呈无色
B:向氯化铁溶液中滴加适量的硝酸银溶液,振荡后静置,溶液黄色未消失
C:向氯化铁溶液中滴加适量的氢氧化钠溶液,振荡后静置,溶液黄色消失
D:观察铁丝在氧气中燃烧的产物为黑色
单词拼写
1930年新年刚过,***受到林彪的一封信,信中写出了他对时局和革命前途流露出一股悲观情绪。***回复了《星星之火,可以燎原》这封信,鼓舞了林彪和其他同志的士气。这说明( )
Jane:Tom , a boy is in the classroom (教室) . Can you guess who he is?
Tom:OK. A boy? ____
Jane:Yes , he is very tall.
Tom:Does he have blond hair?
Jane:No, ____
Tom:Black hair? ____
Jane:That's right. He has a wide mouth.
Tom:____
Jane:Yes , he has big eyes and a big nose.
Tom: ____
Jane:Yes, you're right.
A. his hair is black.
B. Are his eyes big?
C. Is he tall?
D. Is his mouth wide?
E. Oh, I think he is Jim.
(2015•百色)如图所示,小红能把饮料吸进嘴里是利用了____ 的作用,用力捏一下饮料瓶,饮料瓶变扁了,这说明力可以使物体发生____ .