如果Word2000打开了多个文档,下列的操作中,可以退出Word2000的是【】
A. 单击“文件”菜单中的“关闭”命令
B. 单击“文件”菜单中的“退出”命令
查看答案
[A] modern medical instruments are used
[B] they can cure more diseases and save more lives
[C] they have much more medical experience than before
[D] they are too busy to have time to talk with patients
生物进化和新品种选育的4大要素是______、______、______和______。
孢子体不育是指______控制的雄性不育类型,其花粉的育性表现为______。而配子体不育是指______控制的雄性不育
聚合酶链式反应。又称PCR反应,其主要包括______、______、______3个步骤。