...and you see the four standard Aspects along the top:
Note also that two verb types are represented for each Tense/Aspect:
Finally, note the allowance for the "-s" associated with the 3rd person, singular, Simple Present ("writes" and "walks").
Of course, you also need to know what the various tenses and aspects actually mean, but that's outside the scope of this short guide.
*Bill walking his dog.
We can break this down into the standard Subject/Verb/Object structure:
Here's the important idea:
|Looking at the Tense/Aspect chart, you can see that there is no Tense/Aspect which is "walking", all by itself.|
So what would be the fix to the bad sentence shown above?
-ing form of the verb (the Present Participle) is a
progressive form. So assuming you do want a
progressive sense, six forms are permitted. They're shaded in
light green in the little chart on the
right, and here's what happens if you use them to fix the sentence:
|Present Progressive||Bill is walking his dog.|
|Past Progressive||Bill was walking his dog.|
|Future Progressive||Bill will be walking his dog.|
|Present Perfect Progressive||Bill has been walking his dog.|
|Past Perfect Progressive||Bill had been walking his dog.|
|Future Perfect Progressive||Bill will have been walking his dog.|
Note, of course, that not all of these forms are desirable. You want to choose the right one; the one that best expresses what you want to say.
However, the above forms are grammatically correct.
*Bill is walked his dog.
Again, let's break this down into the standard Subject/Verb/Object structure:
|Bill||is walked||his dog|
If you look at the chart, you'll find there are four
tense/aspects that use the
-ed (Past Participle). The
little chart on the right shows them shaded in light blue. Given that you do want to
use a Past Participle, here's what the sentence looks like if you
apply each of these four fixes:
|Simple Past||Bill walked his dog.|
|Present Perfect||Bill has walked his dog.|
|Past Perfect||Bill had walked his dog.|
|Future Perfect||Bill will have walked his dog.|
So now that you can tell which forms are correct, which one should you use? I'll give some ideas in another of these ClickFix pages.