下列说法中正确的是 A． 镁在空气中或纯净氧气中燃烧的产物都只有MgO B． 钠在敞口容器中存放或在空气中燃烧的产物都是Na2O2 C． 将四氧化三铁溶解于
He is the only person who saw the accident . So he is the most important witness . A．happen B．to happen C．having happened D．happened
20.如图，直三棱柱ABC—A1B1C1中，∠ACB＝90°，AC＝1，CB＝，侧棱AA1＝1，侧面AA1B1B的两条对角线交点为D，B1C1的中点为M. （Ⅰ）求证CD⊥平面BDM；（Ⅱ）求面
通过对实验的观察、分析推理、得出正确的结论是化学学习的主要方法之一。对下列实验事实或现象的解释正确的是A．KI淀粉溶液中通入Cl2，溶液变
句型转换。 1.His name is Mike.(改为同义句) 2.My pencils are under the desk.（对划线部分提问） 3.This is a new book.(改为复数句) 4.Are these your cousins?（作否定回答） 5
(2009·四川模拟)某同学设计了如图所示的电路测电源电动势E及电阻R1和R2的阻值．实验器材有：待测电源E(不计内阻)，待测电阻R1，待测电阻R2，电压表(
Tom, you should remember to return the book to name is on it. A．what B．which C．whosever D．whose
I have ______ the Golf Club for over 10 years, said Jack.A. been in B. joined in C. taken part in D. joined
