As I mentioned earlier also that for those fields whose translation does not exist by default system show those fields in default language rather than showing them blank.
And the only way around is to translate those fields manually.
@duongledong4 At the front-end the option to choose language appears in the footer block.
But it will only appear if you have installed two or more languages.
If only one language is installed on your website then the option will not appear as then there is no use of it.