视频选集 starter1-A starter1-B starter2-A starter2-B starter3-A starter3-B unit1-A unit1-B unit2-A unit2-B unit3-A unit3-B unit4-A unit4-B unit5-A unit5-B unit6-A unit6-B unit7-A unit7-B reading plus-1 reading plus-2 reading plus-3 reading plus-4 reading plus-5 reading plus-6 reading plus-7 vocabulary in each unit（单词） vocabular from primary school（小学单词） reference word list(参考单词)
