Foreigners often make some strange mistakes in Chinese when they study the most difficult language--- ---Chinese. We try to analyze typical sentences to correct these errors.

         Yǐjīnɡ 9 diǎn le, tā kéyǐ lái mɑ?
False: 已经9点了，她可以来吗？
          Yǐjīnɡ 9 diǎn le, tā huì(nénɡ)lái mɑ?
True: 已经9点了，她会（能）来吗？

原意是询问“她来”的可能性，也是一种猜测估计，“可以”没有这种用法，应改为“会”或“用”。
This sentence inquiries the possibility of 她来. It also involves the making of an assumption. 可以 has no such usage. One should use 会 or 能.