Lesson 21:Books or computers?

课文目录与封面
Unit 1:Spring is coming!
　　Lesson 1:How's the weather?
　　Lesson 2:It's getting warmer!
　　Lesson 3:The sun is rising
　　Lesson 4:The spring city
　　Lesson5:Babysitting on a Spring Day
　　Lesson 6:Stories about spring
　　Review:Unit Review
Unit 2:Plant a plant!
　　Lesson 7:Planting trees
　　Lesson 8:Why are plants important?
　　Lesson 9:Gardening with Mary
　　Lesson 10:Make your garden grow!
　　Lesson 11:Amazing plants
　　Lesson 12:Danny's plant
　　Review:Unit Review
Unit 3:Animals are our friends
　　Lesson 13:Danny's big scare
　　Lesson 14:Amazing animals
　　Lesson 15:The zoo is open
　　Lesson 16:The bear escaped!
　　Lesson 17:Save the tigers
　　Lesson 18:Friendship between animals
　　Review:Unit Review
Unit 4:The internet connects us
　　Lesson 19:How do you use the internet?
　　Lesson 20:A computer helps!
　　Lesson 21:Books or computers?
　　Lesson 22:Travel on the internet
　　Lesson 23:The internet - good or bad?
　　Lesson 24:An E-mail to Grandpa
　　Review:Unit Review
Unit 5:Buying and selling
　　Lesson 25:Raising money
　　Lesson 26:Cookies,please!
　　Lesson 27:Business English
　　Lesson 28:Mr. Liu's great idea
　　Lesson 29:How to push a product
　　Lesson 30:A cookie sale
　　Review:Unit Review
Unit 6:Be a champion!
　　Lesson 31:Don't fall,Danny!
　　Lesson 32:My favourite record
　　Lesson 33:2800 years of sports
　　Lesson 34:Modern Olympics
　　Lesson 35:The dream team
　　Lesson 36:Classroom Olympics
　　Review:Unit Review
Unit 7:Know our world
　　Lesson 37:Let's learn geography!
　　Lesson 38:The world is a big place
　　Lesson 39:Ring up or call?
　　Lesson 40:Body language
　　Lesson 41:A class of the world
　　Lesson 42:North America
　　Review:Unit Review
Unit 8:Save our world
　　Lesson 43:Let's clean up!
　　Lesson 44:Environment clubs
　　Lesson 45:Let's sort garbage!
　　Lesson 46:Protect our environment
　　Lesson 46:Connected to nature
　　Lesson 48:Garbage is interesting!
　　Review:Unit Review
Pronunciation
Vocabulary and Structures
Grammar