FOR vs SINCE: markers of the Present Perfect Tense

IDIOMS REFERENCE SITES

Idioms or Idiomatic expressions

Idioms are a part of the figurative language. The good thing about them is that they make a language sound very creative, and can also get others to think and figure out what the person who is using the idiom might mean. Unfortunately, they are usually complicated and hard to remember. But they are worth the hassle!!!
Here you are two interesting sites about IDIOMS

1) English at Home
2) Saber Inglés

British English vs American English

Here you are two images showing the differences, spelling and voabulary wise, between Br.E. and Am.E.

Modal Verbs classified

Here you are a classification of Modal Verbs with examples of the different uses of each modal.