单项选择题
已知A、B、C、D分别是AlCl3、BaCl2、FeSO4、NaOH四种化合物中的一种,它们的水溶液之间的一些...
未知题型已知A、B、C、D分别是AlCl3、BaCl2、FeSO4、NaOH四种化合物中的一种,它们的水溶液之间的一些反应现象如下:(1)A+B→白色沉淀,加入稀HNO3,沉淀不溶解.(2)B+D→白色沉淀,在空气中放置,沉淀由白色转化为红褐色.(3)C+D→白色沉淀,继续加D溶液,白色沉淀逐渐消失.由此可知,A是,C是.
I hoped diligence could make up for lack of preparation...
单项选择题I hoped diligence could make up for lack of preparation. On weekend nights, when my American roommates were out on dates, I would stay in the library reading the I visited the writing tutor for every paper I turned in. My papers were always written days before they were due. I lingered after classes to question professors. My classmates lent me their notes so I could learn the skill of note-taking in English. Q: How did the writer develop her paragraph? A、with cause-and-effect pattern B、with comparison and contrast C、with examples D、with problem-and-result pattern
如图5—12所示,一质量M=90g的木块静止在光滑水平桌面上,一质量m=10g的子弹以水平速度V0=400m/...
未知题型如图5—12所示,一质量M=90g的木块静止在光滑水平桌面上,一质量m=10g的子弹以水平速度V0=400m/s射入木块但未穿出.在此过程中,子弹和木块间的摩擦力对木块所做的功为__________,摩擦力对子弹所做的功为__________,因摩擦力做功而损失的机械能为__________.