SINCE AND FOR

http://www.grammarbank.com/since-vs-for-exercises.html

FOR - SINCE

http://www.englisch-hilfen.de/en/exercises/confusing_words/since_for.htm

FOR AND SINCE

http://www.ego4u.com/en/cram-up/vocabulary/since-for

unit 2 present p. past simple

http://www.ego4u.com/en/cram-up/grammar/simpas-preper/exercises?ex07http://www.ego4u.com/en/cram-up/grammar/simpas-preper/exercises?ex08

unit 2 present p. past s.

http://www.ego4u.com/en/cram-up/grammar/simpas-preper/exercises?ex06

unit 2 past s. present perfect

http://www.ego4u.com/en/cram-up/grammar/simpas-preper/exercises?ex05

Unit 2 present p. and past s.

http://www.ego4u.com/en/cram-up/grammar/simpas-preper/exercises?ex03

Revision Unit 2

Unit 2 REVISION FOR THE EXAM: PRESENT PERFECT AND PAST SIMPLE EXERCISES

http://www.ego4u.com/en/cram-up/grammar/simpas-preper/exercises?ex02

Matemáticas - Tema 1 - Jerarquía de operaciones

Jerarquía de operaciones