bettery should be replaced while mian power is "ON"

bettery should be replaced while mian power is ON 英语菜鸟问这句简单的句子怎么解释?什么句型?bettery should be replaced while main power is ON If you're innocent,it should be no problem.如题 should be should be 求翻译,求讲解.We're safer in a train than we should be if we （travelled）any other way.than we should be怎么解释呢? 为什么用should be呢? in order to be a good learner,you should c()what you're learned with something new. You're Gonna Be you're be mentioned should be should do呢？ two should be enought.should May Be You 're My we're meant to be should criminals be punished with length jail terms or re-educated and rehabilitated,using coummunity service programs for instance,before being reintroduced to society? should criminals be punished with length jail terms or re-educated and rehabilitated,using coummunity service programs for instance,before being reintroduced to society? should criminals be punished with length jail terms or re-educated and rehabilitated,using coummunity service programs for instance,before being reintroduced to society? 翻译：It used to be a house or car, says Carlson.Now you say, 'you're busy? You should see how busy we are.' We're safer in a train than we should be if we （travelled）any other way.为什么句子前面没用虚拟?后面却用虚拟了?