# A plural and a definite article in relationship

If pens is mentioned already and one of them is broken, which shoud I say, A pen is broken or The pen is broken?

If all that has been mentioned before is a collection of pens, then you must say

A pen is broken

because we do not even know whether one or more pens is broken. Even if only one is broken, we have no way to identify it.

If, however we had previously said

There are ten pens on the teacher's desk, only one of which is red.

Then we could later say

The red pen is broken.

Moreover, if we said

There are ten pencil's on the teacher's desk, but only one is broken

then later we could talk about

the broken pen

in reference to that collection of pens.

If pens has been mentioned already, then the collection of pens is known, and the pens would be natural.

But the pen would imply that you expected the hearer to know which of the pens you were referring to.

This doesn't matter.

What does matter is the answer to these two questions:

• Does it matter which pen you are talking about?

• Do you expect the listener/reader to know which pen you are talking about?

If the answer to both questions is yes, then you use the X.

If the answer to both questions is no, you use a/an X.

If the answer is yes, then no, then you have use a determiner other than an article or explicitly tell the listener/reader which pen you are talking about.