这是很多人都遇到的。一开始把输出分辨率调好。或者自己转换成pdf后再上传

用矢量图应该就不会有这种问题

矢量图，600dpi可以

You can increase the pic resolution. But even that will not help. Normally, the pdfs are produced with low resolution images to reduced the size of the file. Some journals have an additional link from the pdf that allows the reviewer to download a high resolution. So, it may not be that important.

This is sometimes a problem. I myself have encountered manuscripts where the images do not have enough resolution. But its because the publisher want to reduce manuscript size，

这不是问题，如果不放心，再发一遍WORD版给编辑就行

这是投稿系统在线PDF转换工具的问题。只要不影响审稿人的阅读判断，应该就没有问题。