I have a big problem about when I must use possessive "S". I've tried so many times to understand its indication, but I failed. it may appears easy, but for me it's very confusing, let me give you some examples :

  • Rosner's team plans to explore the possibility of a clinical trial involving people with mild cases of COVID-19 : can we just say Rosner team plans to... ?
  • Today's English tip, we are just going to talk about time zone : normally we have to say "the English tip of today", but can we say "Today English tip..." ?? I have been facing too many situations where I don't know what to use, either possessive s or not, but I don't remember all of them right now 😕

1 Answer 1


In the first case, using the possessive indicates that Rosner is the leader (or at least a member) of the team. This means that there is a possessive relationship. Rosner owns the team (in some sense) by leading it. Rosner is the leader, not an attribute of the team.

Using Rosner as a noun adjunct "Rosner team" would be unusual, though it could mean "the team that is using techniques invented by Rosner". That would be rare but for example:

The Stanislavski team will learn method acting. (Stanislavski isn't the team leader, but his name is used to name the team.)

A possessive can function as a determiner, but a noun adjunct can't. So you need an article: "The Stanislavski team". But not "The Rosners's team"

Similarly, the relationship between the "tip" and "today" is possessive. "Today" has "this tip". You wouldn't say that "The tip is made of today" or that the tip has any particular properties of a day. So it is natural to say "Today's tip". In fact, that is more natural than "The tip of today".

There is also a lot of idiom. There is no real reason why we say "Today's fish" but "The fish of the day", except idiom. And idiom doesn't follow rules, you just need to gradually pick up the idiomatic expressions.

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