MarketWatch on MSN: You only really need to know one thing to save for retirement You only really need to know one thing to save for retirement 0 The phrase 'one of the' is used to describe something/someone from the same group. There are many birds on the tree. One of the birds is red.

Understanding the Context

This means we are talking about all the birds on the three but then when you want to be specific about the red bird, you use one of the. He is one of the soldiers who fights for their country - is correct. The 'one hand' could be any generic hand (no article) or a specific one (definite article). 'The other' refers to the 'matching hand' of the first one.

Key Insights

There can only ever be one, and it is being referred to explicitly as the partner of the first, therefore it needs a definite article. One-to-one is used when you talk about transfer or communications. You may use one-to-one when you can identify a source and a destination. For eg., a one-to-one email is one sent from a single person to another, i.e., no ccs or bccs. In maths, a one-to-one mapping maps one element of a set to a unique element in a target set.

Final Thoughts

One-on-one is the correct adjective in your example. See Free ... Which one is grammatically correct or better? I have two assignments, One of them is done. I have two assignments, One of which is done. I watched a video tutorial that the teacher said the ...

pronouns - "One of them" vs. "One of which" - English Language Learners ...