The form of the possessive/genitive case

What should I use? "'s form" or "of sthg form" to express possession?
Here is the answer:
's
- A 's is used with singular nouns and plural nouns not ending in s:
► a man 's job
► the people 's choice
► men' s work
► the crew' s quarters
► a woman' s intuition
► the horse' s mouth
► Russia 's exports

- A simple apostrophe (') is used with plural nouns ending in s:
► a girls' school
► the students' hostel
► the eagles' nest
► the Smiths' car

- Classical names ending in s usually add only the apostrophe:
► Pythagoras' Theorem
► Archimedes' Law
► Sophocles' plays

- Other names ending in s can take 's or the apostrophe alone:
► Mr Jones 's (or Mr Jones' house)
► Yeats 's (or Yeats ') poems

of + noun:

- When the possessor noun is followed by a phrase or clause:
► The boys ran about, obeying the directions of a man with a whistle.
► I took the advice of a couple I met on the train and hired a car.

- With inanimate 'possessors', except those listed in above:
► the walls of the town
► the roof of the church
► the keys of the car

- It is often possible to replace noun X + of + noun Y by noun y + noun X:
► the car keys

- The first noun becomes a sort of adjective and is not made plural:
► the roofs of the churches = the church roofs

Unfortunately noun + of + noun combinations cannot always be replaced in this way and the student is advised to use of when in doubt.

Sources: A Practical English Grammar. Thomson & Martinet. Oxford University Press, 1986.

Classic/classical - Economic/economical

Classic or classical? Economic or economical? Which one is correct?

CLASSIC: something that it is among the best or most typical of its class; serving as a standard or model.

CLASSICAL: something that belongs to a traditional style or set of ideas. Classical music. Beethoven, Mozart's music.

ECONOMIC: something related to trade, industry, economics.

ECONOMICAL: something not wasteful, money-saving

Try these:

ON + days or dates / IN months

First of all, don't forget that days and months are always written with capital letters.

And when you are using days or dates, the right preposition used is ON:


ON with Days and Dates

ON Monday, ON Wednesday.
ON January the 1st, ON the 10th of March.

BUT:
IN with Months
IN February, IN July...

I was born ON April 21st but my wifes' birthday is IN August.

What about you? When were you born? When is your best friend's birthday?

Avoiding the word "important"

Students usually use the word "important" so many times that they flood oral and written productions with this term.

This may occur because they don't realize they can paraphrase this expression by using words they already know.

Therefore, if you are a student, when you are about to use the expression "it's important", think of all these other expressions in order to paraphrase it:

It's essential, crucial, considerable, critical, decisive, determining, imperative, meaningful, necessary, substantial, and so on and on. More synonyms here!