# “A is the property of a system that regulates” or “A is the property of system by which it regulates”

Let a system S has a property A. I want to say something like this,

• A is the property of a system that regulates the concentration of Sodium ions. Or,

• A is the property of system which regulates the concentration of Sodium ions.

I think it says that A is found in a systems which regulates the concentration of Sodium ion. I am OK with it, but not happy. I thought following would better for it emphasizes A.

• A is the property of a system by which it regulates the concentration of Sodium ions.

One of my friend (not a native speaker) thinks that both sentences are equivalent and the former has the advantage of using less word to convey the same. I think that second one has different meaning.

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Sodium ions should be plural, and you probably should refer to a property of the system. – Bradd Szonye Oct 18 '13 at 20:47

I think you have your articles mixed up in both sentences. Try these:

``````A is a (or the) property of the system that regulates the concentration of sodium ions.
``````

Or

``````The system that regulates the concentration of sodium ions includes property A.
``````

Or

``````Property A is the property of the (or a) system which regulates the concentration
of sodium ions.
``````

Or

``````Property A regulates the concentration of sodium ions in the (or a) system.
``````

I think it depends on whether you have several properties in the system, or several systems which include different properties, or several systems that all included property A. If you say a system then there could be several possible systems and property A could be specific to that one system or other systems. If you say the system then that might be the only system for regulating sodium ions. If you say a property A then you are saying one property of the system functions as the regulator. Normally we do not use a in front of a specific property. Instead we say the property A regulates... or just Property A regulates... If I were writing the lab report, and there was more than one possible system I would write:

``````Property A regulates the concentration of sodium ions in this system.
``````

I was careful to designate a specific system with the word this. I would not say this is the only property that regulates..., because I might not be correct if I am a beginning lab student.

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