I already added Chinese input method into ibus but when I switched to it the Chinese input symbols(bopomofo) wouldn’t appear, just English letters appears every time I hit the keys of the keyboard. I don’t know why.
Ibus is not installed by default, did you install ibus and ibus-qt, etc. first?
Did you also add the equivalent to System Settings > Account Details > Locale?
By adding it there, System Settings > Account Details > Language packages (from Manjaro Settings Manager) will be able to detect any language packages needed by the system, and or other application (aka firefox, thunderbird, hunspell, etc.), and prompt you for their installation.
I did as you said and it works now! Thanks for your help.
P.S. The characters of the ibus menu won’t display properly(in fact, they would be a mess and entirely can’t be read) if I switch to Chinese input method, I think it’s a little (compatibility) problem.