Then I have found this: CTRL SHIFT assigned to keyboard layout change. In the Tweak Tool under Keyboard and Mouse/Additional Layout options/Switching to another layout had CTRL SHIFT checked! I have unchecked it and now I can use all my favorite shortcuts (only now I've realized that there are so many).

总体来说，就是：

1.安装tweak tools

2.打开tweak，打开键盘和鼠标tab项

3.在右边找到“其它布局选项”并打开它

4.找到“切换至其它布局”里的Ctrl+Shift，取消勾选即可。