这是我用过最好的学习类app，有3点建议：
一、希望在ipad横屏下阅读两页。
二、支持的格式太少，希望增加对TXT. MOBI 等格式的支持。
三，希望笔记能分享给WPS 和有道云笔记等app
This is the best learning app I've ever used. I have three Suggestions:
1. I want to read two pages on the horizontal screen of the ipad.
2.There are too few supporting formats, and we hope to increase support for formats such as txt.mobi.
3.I hope the notes and mind maps can be Shared with apps like WPS and youdao cloud notes.
Thank you!