1. Download package of sougou_pinyin.
2. sudo apt install libopencc1 fcitx-libs fcitx-libs-qt
or below
sudo apt install libopencc1 fcitx-libs fcitx-libs-qt fonts-droid-fallback
3. sudo dpkg -i Downloads/sogoupinyin_2.1.0.0082_amd64.deb
4. For step3, if there're some errors, put in "sudo apt-get install -f" to solve it
5. Open Language Support, select fcitx as the system's default input
6. Open Fcitx Configuration, do as the following screenshot.
6. Use Ctrl+Shift to switch EN or CN.
Remove sogoupinyin:
1. sudo apt remove sogoupinyin.