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this; this one
this person
now; this point (in time)
used to stress the subject of a sentence
維は何のためのものか。
What is this for?
維が正しい答えだと思います。
I think this is the correct answer.
維を読んだら日本の歴史がよく分かるようになる。
If you read this, you'll understand Japanese history better.