唔該幫我睇下句英文有無錯文法~~

The KCRC and the MTR was merged between 1980 and 2000. ( The years Not true )
↑Use passive voice
The KCRC merged with the MTR.
↑Use active voice
The KCRC and the MTR have merged in the year between 1980 and 2000.
↑Use present perfect tense

merger 係noun
如果在present perfect tense,冇verb ( 如：merged 等 ),而只有adj ,noun等
就用have been ( 如：I have been at home for three days.
''have" 後只有at(preposition) home,,)
又如：I have been a teacher since 2000. . 只有a teacher ( noun )
咁樣先會用been.
但merger係noun,又唔同a teacher 喎,
merger係有個verb叫merge
把merge 轉做present perfect tense的merged就..
無須加been,,後者又用merger

"Merger" is a noun.

Consider this:

The merger of KCRC and MTR has been done between 19xx and 20xx.

For your reference, your original sentence should be as follows:

The KCRC and MTR have been merged between 19xx and 20xx.

Hope this is useful.

The KCR and MTR have been merged within the years of 19XX and 20XX.

KCR and MTR 要大階.
merger 係名詞, merge先係動詞,被動+ed.

The KCRC and MTR have been mergerd since 19XX.