It will not be directly apparent a virus exists while it is memory resident.

This came from a description of a computer virus in the Microsoft website, but I cannot understand the structure since there are two verbs (be and exists) in the main clause. Referring to the google translation, I think it would likely mean...

The fact that a virus exists while it is memory resident will not be directly apparent.

I still don't understand why the main clause should have the two verbs and if that is really grammatically correct. Could somebody explain in detail?

  • 3
    This is a case of that omission: It will not be directly apparent [that] a virus exists.
    – fev
    Jan 16, 2023 at 13:38
  • 1
    In my opinion your rephrasing changes the meaning.
    – nnnnnn
    Jan 16, 2023 at 13:52
  • 2
    @fev What's with this bizarre fear of using that sweeping the land? Strange.
    – tchrist
    Jan 16, 2023 at 14:26
  • @tchrist Economy of language maybe? But I wouldn't compromise the lack of ambiguity for the sake of being economic... I don't get it either.
    – fev
    Jan 16, 2023 at 14:43
  • It's certainly not a good sentence: the scope of the while clause isn't immediately obvious. Compare "It is not widely believed a woman is happy while she is unmarried", which probably has the opposite scope.
    – Stuart F
    Jan 16, 2023 at 15:06

2 Answers 2


Matrix clauses contain two or more verbs typically occurring in one or more embedded subordinate clauses.

Here, the matrix clause (the whole sentence) contains a number of subordinate clauses.

The detailed clause bracketing is:

[It will [not be directly apparent [a virus exists while [it is memory resident]]]].

From this, we can see that the matrix clause (in outer brackets) contains three embedded subordinate clauses.


Your interpretation is correct. You have an “anticipatory it” standing in as a dummy subject for the true subject, which appears later in the sentence.

Your true subject is a “zero thatthat-clause. Here is your sentence showing the that of the that-clause:

It will not be directly apparent [that] a virus exists while it is memory resident.

Here it is with the true subject at the beginning:

That a virus exists will not be directly apparent while it is memory resident.

Adding the fact in front (The fact that a virus exists . . .) makes the that-clause an appositive, but the meaning is the same with or without the fact.

Further reading on zero that and extraposition with that-clauses: ThoughtCo: ’That’-Clause


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