Duplicate Matching With Multiple Criteria Across Multiple Worksheets

I'm an ESL (English as a Second Language) elementary school teacher in Taiwan who is looking to make a mini dictionary (extended glossary) for my students.

I have the raw data separated with one worksheet for each grade (6 grades in total).

In each worksheet
Column A = English words used in their books
Column B = the part of speech (noun, verb, adjective etc.)
Column C = the Chinese translation
Column D = where I want a VBA script to tell me is a word has been previously taught.

What I need now is to mark which words are duplicates in column D, but only where the text in all three of columns A B and C already exists in a previous grades worksheets.

All three columns of a row need to match because the same English words can be the same part of speech have multiple meanings...
e.g. tank = fish tank, army tank, water tank

... and the same Chinese translation can be used for multiple English words...
pocket money = 零用錢, allowance = 零用錢

I want to check for duplicates only against the words in the worksheets for grades they've already finished.
e.g.
I want to check the grade 2 words against the words in the grade 1 worksheet.
I want to check the grade 3 words against the words in the grade 1 and 2 worksheets.
I want to check the grade 4 words against the words in the grade 1, 2, and 3 worksheets. etc.

Any help anyone could give me would be much appreciated.