选出每组单词中不同类的一项：(   )

A．black

B．yellow

C．desk

选词填空。
school   cars   easy   air    exercise    use
Many people in the world ride bicycles every day. There are more bicycles than ________ in the world today. A lot of Chinese people ride bicycles to go to work or ________. Bicycles are much cheaper than cars. And it is ________ for people to learn to ride. Bicycles are also used for ________. It helps us to keep fit. If each family has a car, it will ________ a lot of energy and pollute the ________. So let us ride bicycle.

根据图片补充单词。
1. w _ _ _ e _
2. f _ _ s _
3. s _ _ o _ _
4. d _ _ _ k
5. t _ _ _ d

He’s good man. He’s helping a _______. (   )

A．children

B．child

C．childrens

crayon （  ）

A．水笔

B．蜡笔