A dollar barely gets you anything today, but back towards the end of the 20th century, it was somewhat decent spending money. These days, everyone seems to be scraping by on money to get through the ... One-to-one is used when you talk about transfer or communications.

Understanding the Context

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. One-on-one is the correct adjective in your example.

Key Insights

See Free ... "Which one is the best" is obviously a question format, so it makes sense that " which one the best is " should be the correct form. This is very good instinct, and you could even argue that the grammar is good, but at best it's unnatural. On the one hand, I really enjoy pie, but on the other hand, I’m supposed to be on a diet. Both of these expressions use each hand to represent an opinion, as if weighing the pros and cons of each choice with the hands as the scale.

Final Thoughts

idioms - "On one hand" vs "on the one hand." - English Language ... How one and one's is different from other indefinite pronouns The possessive of one (one's) is formed the same way as the possessive of other indefinite pronouns, such as someone (someone's), but it is used a bit differently. For most people, one is consistently used with the possessive form one's. With one or more is / are, the first thing to consider is whether 'one or more' is a unit or analysable. It has the near-synonym 'some'; 'four or five' could be substituted reasonably by 'several'. Which is correct: "one or more is" or "one or more are"?