1. Computers are not connected to the Internet: Without computers connected to the Internet, rice husk readers cannot get the latest contents and highlight lines.
2. Problems with the rice husk reader software itself: There are problems with the rice husk reader software itself, and the version is too low or the software is damaged, which will make it impossible to use the highlight line drawing function.
3. Improper operation: improper operation when using rice husk reader to highlight lines, failure to select words to highlight or failure to draw lines with correct tools, resulting in the inability to use the function of highlighting lines.