I do not know whether I can use the form of must in subjunctive:

The participation subjugated to the constraint that,

  • the car must be new

  • the car be new

Must expresses the duty, but it is not a verb. Does have to have to be used ?

  • Why is it not a verb? You can connect it with "I, you etc", so it must be a verb.
    – rogermue
    Apr 18, 2014 at 11:01

2 Answers 2


One problem with this question is that the preamble is not idiomatic English, and so it is difficult to parse the bullet points.

If the preamble says:

Buyer's participation is subject to the constraint that:

then the correct bullet point is in fact:

The car must be new.

If you leave out "must", people will understand your meaning, but including "must" makes it more idiomatic. If you leave out "must," "is" instead of "be" sounds more idiomatic to my ears at least.

If the preamble is formed a little differently, it would definitely be appropriate to use "the car is new" (probably not "the car be new"):

Buyer will participate in this transaction only in the event that: the car is new.


The first half of your sentence does not make sense, so I will guess that "participation is subject to the constraint that" is what was intended here.

You are correct that you would not use "must" with the subjunctive. For example, the sentence "I insist that you turn in your paper" is a correct use of the subjunctive, but it is not grammatically correct to say, "I insist that you must turn in your paper." Must is associated with the imperative, as in "You must turn in your paper."

To help clarify why "the car be new" is the correct ending: "participation is subject to the constraint that the car be new" can be paraphrased as "we insist that the car be new."

The way the each fragment is posted on it's own line makes "the car must be new" look more grammatical at first glance, because it is a complete sentence, whereas "the car be new" is not.

As a note, must is, in fact, a verb: see the Merriam-Webster definition. That said, it is an auxiliary verb (also known as a helper verb or modal verb), and so cannot be used on it's own.

"To be", on the other hand, is both an auxiliary verb and a regular verb. This means that in some cases it accompanies another verb, like "I am going" and other cases, you use it by itself: "I am happy."

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