A:①②③
B:②③④
C:①③④
D:①②③④
如图是草原生态系统中兔数量与植物数量变化的模式图.
I'd like to go swimming _______ the water is too cold.
单词归类。
student coat tie bus stop vet policeman panda pajamas shoes socks lion leopard post office jeans jacket sweater dancer zebra toilet rabbit pilot juggler snake swimming pool tiger movie theatre goat trousers sheep bank fox fire station squirrel monkey frog zoo horse giraffe shorts shirt library park hospital restaurant skirt dress pants train station teacher police station school nurse supermarket doctor
根据汉语意思完成句子。
选项
实验目的
实验方案
A
检验CH3CH2Br在NaOH溶液中是否发生水解
将CH3CH2Br与NaOH溶液共热。冷却后,取出上层水溶液,用稀HNO3酸化,加入AgNO3溶液,观察是否产生淡黄色沉淀
B
检验Fe(NO3)2晶体是否已氧化变质
将Fe(NO3)2样品溶于稀H2SO4后,滴加KSCN溶液,观察溶液是否变红
C
验证Br2的氧化性强于I2
将少量溴水加入KI溶液中,再加入CCl4,振荡,静置,可观察到下层液体呈紫色
D
验证Fe(OH)3的溶解度小于Mg(OH)2
将FeCl3溶液加入Mg(OH)2悬浊液中,振荡,可观察到沉淀由白色变为红褐色