题目

Staying at home, no socializing and wearing a face mask if going anywhere have proved to be the most ________ ways to prevent the spread of the novel coronavirus. A . effective B . expensive C . miserable D . suspicious 答案：A12．用嫁接的方法来繁殖果树和花卉，成活的关键是（　　）A．接穗要保持湿润B．接穗和砧木的选择C．嫁接的时间要选择好D．接穗和砧木的形成层紧密地结合在一起