Can you identify which one of these sentences is wrong?

I laid my weary body on the bed.

For a long time, I was just laying under the covers.

I really wanted to lie there all day.

But eventually, I had lain around enough.

Yes — the second one is grammatically faulty; but do you know why?

Here at “Weird Words,” we’ve been sitting on grammar for the past month — ever since I felt the need to explain my use of ain’t in one earlier column.

So after laying that to rest — and dealing as well with split infinitives, terminal prepositions and the tricky who-whom — we’ll finish this short series with one of the snarliest grammar issues in the English language: lay, lie, laid and lain.

But once again, it’s going to involve some nuts and bolts.

The first thing to say is that none of the confusion involves lie in the sense of telling an untruth; the forms of that verb are always lie, lied or lying.

Yet it’s worth mentioning, because that sense of lie is a good example of what’s called an intransitive verb. I know, I know: That sounds off-putting; but it’s relatively simple.

A transitive verb is an action done to something: He tackled his opponent. (That is, you can’t just say “He tackled”; it makes no sense.)

An intransitive verb does not have an object it acts upon. For instance, agree, flow and sneeze are always intransitive: you can’t flow something, or sneeze something else.

On a related and mildly interesting note: With the advent of TV remotes, the verb pause suddenly became transitive; before that, you could not pause anything!

And like pause, most verbs can be both transitive or intransitive; you can eat a meal, or you can just eat. But that is not the case with lie and lay.

Lay is a strictly a transitive verb; it means “to put something down.” Its past tense is laid. Thus: “Yesterday we laid some tiles; tomorrow we will lay the bricks.”

Lie, on the other hand, is an intransitive verb, even when it means “untruth” — but that’s not the confusing part; we all know you can tell a lie, but you can’t “lie something.”

The problem is that the other sense of lie is similar to lay: it means to make yourself prone on a flat surface: “I will lie down in bed.” (Notice how both senses often connect to “down.”)

So if you keep that distinction in mind — lay acts on something, lie means being prone — you can avoid the two most common errors of lay and lie:

First, people often say, “I was laying around all day.” Even I myself sometimes mistakenly phrase it this way. But … it should be lying.

Personally, I’m helped on this by recalling Mark Harris’ long-ago novel Lying in Bed; the plot involves adultery — and thus his title cleverly plays on both senses of lie.

So, be likewise careful with the present tense of lie: “I think I will lie down for a bit.” You should never say, “I will go lay down.” Lay can’t be intransitive.

But the real confusion comes with the past tense of lie — which is … lay. And that gives us admittedly awkward sentences like this: “This morning, I lay in bed till my alarm went off.” Or: “She lay on the floor to watch TV.”

And last but not least: The past participle of this lie — that is, the form used with has, had or have — is lain: “Go get him up; he has lain in bed too long.” (Thankfully, these cases don’t come up much in speech or conversation!)

So to sum it all up:

Lay is an action done to something: “He laid down his weapon.” Lie means becoming prone: “I should lie down.” The latter takes such other forms as lying and lain; you can’t say, “I was laying in bed,” as I did at the beginning of this piece.

And finally: The weird past tense of lie is lay: “Our lazy dog lay on the floor all day.” There is no layed. You spell that laid, and use it only as a transitive:

“Smith was done with grammar — so he laid down his pen.”

Thank God for that.