搜题请搜索小程序“爱下问搜题”
问题 选择题

盐是一类常用物质，下列物质可直接形成盐的是[ ]

①金属②碱性氧化物③碱④非金属⑤酸性氧化物⑥酸

A．只有①②③

B．只有④⑤⑥

C．只有①②③⑤⑥

D．全部

答案

答案：D

判断题

数据容灾系统建设主要目的在于保护数据库在灾难打击之下的存活能力，尤其是要保证在任何灾难打击之下的数据存活能力。（）
查看答案
问答题

Daily exercise makes you feel good. It helps you think better and believe it or not, it helps you sleep better and feel more relaxed. Once you start exercising regularly, you will feel per and keep improving at physical activities. When you exercise, you breathe more deeply and get more oxygen into your lungs with each breath. Your heart pumps more oxygen-filled blood to all parts of your body with each beat. Your muscles and joints feel flexible. Exercise also helps you to stay at a healthy weight.
查看答案