Generally, it is rare to sign the same work or the same correspondent, and the second author signs two people. Except for one work, there is little difference between the two or three authors who signed it later. If you invest in a core journal, unless the contribution of the two works can be tied with that of the first author, the status of the two works can also be improved. If it is a general publication, it is recommended to label two or three works directly, and there is no need to entangle the issue of * * * with two works.