Do you want to be TEFL or TESOL-certified and teach in Bingtuan Jiushi Tuan? Are you interested in teaching English in Bo'ertala Menggu Zizhizhou — Bo? Check out ITTT’s online and in-class courses, Become certified to Teach English as a Foreign Language and start teaching English ONLINE or abroad! ITTT offers a wide variety of Online TEFL Courses and a great number of opportunities for English Teachers and for Teachers of English as a Second Language.
Unit 4 Present tenses includes grammar rules of English language. I agree with the authors of this unit, that “The tense system is  the area of English language that cause students (and often teachers) the greatest amount of difficulty. And about Present Perfect that “The present perfect relates the past to the present and although commonly used by a native speaker, presents some difficulties to the English language learner.” I like part about Typical student errors.