I have multi-lang input switch problem - Linux

I don't type in English on purpose,
and I really want to search questions before asking,
but I can't use chewing input for chinese searching.

Here is my question,
I suddenlly can't switch to chewing input from English.
This happened after I logged out and in.
Before logging out,
I remember I installed Virtual Box and try to learn something,
then VB asked me something about keyboard or typing..
(not sure about what happened exactly)
And I say YES to some settings..probably..?
This is the only clue I have.

I can see the chewing icon if I press SUPER+SPACE key,
https://i.imgur.com/BMWXY7i.png
but I can't type any chinese out,
It is still English.

BTW, I am using Ubuntu 18.04.
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Usually I prefer to google question by my own,
but this issue is tricky,
I don't know what keywords related to it.
And Not every Linux person needs chewing input,
so I try to ask for help here.
Or I have to reinstall Ubuntu again...OMG

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