subjunctive?

zyc50

I just came across the subject of \"subjunctive\" in a usage book, and has yet to figure it out.

e.g. \"It is essential that every child have the same educational opportunities\"

My questions are:
1. How could you tell it's a subjunctive structure, any word that hints? or would people think the writer make a grammatical mistake?
2. Does the usage gain broad currency nowadays?
3. Seems that \"has\" can replace \"have in the example? Not necessarily a base form to be used?

With great thanks.

Subjunctive is usually used to express wish, possibility, or certain conditions where people express regret, impractical wishes, and the like.
"It is essential that every child have the same educational opportunities"
In this example, the complete structure should be :" It is essentical that every child should have the same educational opportunities". The functional word "should" was omitted here, and this is very common in subjunctive sentences.
When you come across sentence patterns like : "It is suggested/required/necessary/essentical/proposed...that +subject+(should) +v.", they are surely subjunctive. It is not hard for you to group words in this category.
According to my personal experience, we are using it every day. Fr example, "If I were you, I would not do that." "If I had studied hard last semester, I would have passed the exam."...
If you want to learn more about this grammatical item, please refer to any grammar book in hand, you will find what you need.