I thought that the use of is/are was determined by whether or not the noun was singular or plural. But also, I'm awful at these things.
username is singular. password is singular.
But we are saying a 'username and password' - in my mind, this is two things. Plural, right?
I thought the correct word choice would be 'are'.
However, when I search for both phrases Google returns 82k results when the phrase uses 'are', but 189k when the phrase uses 'is'. That seems to strongly suggest I'm wrong and that it should be 'is'.
Can someone help me understand?