国际上通用的可允许接触的三种安全电压限值中,安全电压限值最高的是()V。A.小于10 发布时间:2017-07-09 23:45 │ 来源:www.tikuol.com 题型:单项选择题 问题: 国际上通用的可允许接触的三种安全电压限值中,安全电压限值最高的是()V。A.小于100B.小于70C.小于50D.小于36
题型:单项选择题 下列离子方程式正确的是[ ]A.用惰性电极电解饱和氯化钠溶液:2Cl-+2H+H2↑+ Cl2↑ B.用银氨溶液检验乙醛中的醛基:CH3CHO+2Ag(NH3)2++2OH-CH3COO- + NH4+ +3NH3 + 2Ag↓+ H2OC.苯酚钠溶液中通入少量CO2:CO2 + H2O + 2C6H5O-→2C6H5OH + 2CO32- D.Na2SO3溶液使酸性KMnO4溶液褪色:5SO32- + 6H+ + 2MnO4- == 5SO42- + 2Mn2++3H2O 查看答案
题型:单项选择题 根据句意,从方框内选择合适的情态动词完成句子。must, may, can, could, might, can't1. The brown wallet be Tom's or Bill's. They both like brown.2. I haven't seen Alice for several years. She be a big girl now.3. —Whose jeans are these? I found them on the chair in the living room. —They be mine. I put my jeans on the bed.4. — the woman there be our math teacher? —She be, but I'm not sure. 查看答案