Starting your sentence with one of these "false subjects" may not always be the best choice (as I discussed last time in my article Talk About People), but when you do start a sentence with the word there, you'll want to use correct verb agreement.
Consider this sentence I found on the Internet (yes, identity masked to protect the innocent):
While there is a large number of Content Management Systems (CMS) to choose from, few CMS platforms are more popular and more widely used than [system A and system B].
To fix the grammar of this sentence, we'll have to use two different concepts. The first is how to identify the true subject for which the false subject is a stand-in. The second is deciding whether to use a plural or singular verb with the expression a number of.
When you start a sentence with there, the true subject will be after the verb, like this:
There is one cat under the couch.
The true subject is one cat. If we removed the word there, we would use one cat as the subject of the sentence:
One cat is under the couch.
Compare that sentence with this one:
There are two cats under the couch.
Here are some more examples:
There are four good reasons to use System A.
There is only one way to delete the system file.
Now let's add a more complicated true subject:
There is none of this confusion when you start by learning the basics.
There are plenty of reasons for using system B, also.
Finally, let's look at the phrase a number of. The Gregg Reference Manual, an excellent grammar reference book, tells us that the phrase a number of is plural. In contrast, the number of is singular.
So in our original sentence from the Internet, the true subject,a large number of Content Management Systems is plural. The corrected sentence would read:
While there are a large number of Content Management Systems (CMS) to choose from, few CMS platforms are more popular and more widely used than [system A and system B].
I'll save a discussion of not defining an acronym in the plural for another day.
Choose the correct verb agreement in these sentences starting with there.
- There is/are two dialog boxes and three messages yet to get through.
- There is/are some plants on the balcony that need to be brought in before the frost.
- There has to be/have to be compelling reasons for omitting the planning stage.
- There has been/have been such a ruckus about the new upgrade schedule that some developers have turned elsewhere.
- There was/were a number of professional trainers involved in the program's development.