【单选题】根据恒星能源的热核反应理论和宇宙大爆炸模型估算,银河系中最古老恒星的年龄大约在下面( )指示的范围内。
【单选题】今有3.2 ml的5.0 mol·L -1 H 2 SO 4 溶液,密度为1.0 g·mL -1 ,其中1/2H 2 SO 4 ,H 2 SO 4 和H 2 O的物质的量(mol)分别是 ( )
【单选题】今有3.2ml的5.0mol·L -1 H 2 SO 4 溶液,密度为1.0g·mL -1 ,其中 1/2H 2 SO 4 的物质的量(mol),H 2 SO 4 和H 2 O的物质的量分别是( )
A.
3.2 ×10 -2 ,1.6×10 -2 ,0.091
【简答题】传统分析,消费者购买行为的理论是“____”理论,它有两个特点:一是____,二是____十分重要。
【单选题】患者,女性,35岁。因活动后有呼吸困难,近半年有进行性加重,并伴有咳嗽、声音嘶哑。患者11既往有风湿热10年,常有扁桃体炎发生,经医生诊断为慢性风湿性心瓣膜病。二尖瓣狭窄最早出现的症状是
【判断题】A superordinate could not be a superordinate to itself.
【单选题】在H 2 SO 4 、K 2 SO 4 、Al 2 (SO 4 ) 3 和明矾[KAl(SO 4 ) 2 ·12H 2 O]的混合溶液中,H + 的浓度为0.2mol/L,SO 4 2- 的浓度为0.5mol/L,当加入等体积0.6mol/L KOH溶液时,生成的沉淀恰好完全溶解。则反应后溶液中K + 的浓度约为
【单选题】听力原文:W: The dean just announced that Dr. Jeffery is going to take over as Chairperson Of the English Department. M: I knew it all along. He was the obvious choice. Q: What does the man mean? (16)
A.
He doesn't know Dr, Jeffery very well.
B.
He thought Dr. Jeffery would get the position,
C.
He thought it took too long to make the decision.
D.
He's not sure Dr, Jeffery will be a good chairperson.