It is the mandative subjunctive. It is a noniflected form of the verb that follows words such as require, demand, recommend, suggest, etc. You can Google "mandative subjunctive" for more information.
How come the word "wait" in the following sentence doesn't end in S although the subject is third singular. what's the grammar point?
Etiquette only requires that she wait for fifteen minutes.
taken from an article in Top Notch 3.
Last edited by emsr2d2; 06-Jan-2015 at 08:56. Reason: Sorted out formatting and removed unnecessary line breaks
You'll be pleased to know, IRENGLISH, that in everyday conversation most native English speakers never use the subjunctive, even when they are aware of its existence. Its use is not compulsory. In the quoted sentence, 'waits' is just fine for most purposes.
(Richard Nordquist. www.abouteducation)The use of the subjunctive mood in a subordinate clause that follows an expression of command, demand, or recommendation.
Like the formulaic subjunctive, the mandative subjunctive consists of the base form of the verb. It is distinctive only in the third-person singular of the present tense. (In other words, the -s ending is omitted.)
In the Oxford Dictionary of English Grammar (1994), Chalker and Weiner note that the mandative subjunctive "has made a considerable comeback in British English in recent years, probably under American influence." Yet in all varieties of English, the mandative subjunctive is far more common in writing than in speech.
***** NOT A TEACHER *****
Two teachers have already answered your question.
I would just like to discuss the reasoning behind the subjunctive.
"Waits" is the so-called "indicative." The indicative refers to reality: "She waits for the bus for 15 minutes every day." That is a FACT.
"Wait" is sometimes the subjunctive. That is to say, it does NOT refer to reality. It is only someone's suggestion: "It is important [in my opinion] that she wait until she is 21 before getting married." That is not a fact. Maybe she will wait, or maybe she will not wait.
"I demand [that is my order] that you be here at 7 a.m. tomorrow." That is not a fact. Maybe the person will obey me and maybe not.
If you are speaking or writing American English, you may wish to use the subjunctive. For example, I have read that most (not all) Americans still say: "If I were ...." (instead of "was").