Trees can get light from       in the daytime.

A．C02

B．O2

C．the sun

D．the moon

Chlorophyll is in         .

A．sunlight

B．soil

C．air

D．leaves

We can get more O₂ by         .

A．planting more trees

B．cutting trees down

C．making the water in soil(土壤) polluted

D．making more CO2

CO₂ from air and      can produce food  for trees with the help of chlorophyll and sunlight.

A．water in the sea	B．water from soil
C．water in the river	D．O2 into air

The picture tells us         .

A．how trees let O2 go into air in the sunlight

B．how trees let CO2 go into air in the sunlight

C．the sunlight isn't important to trees at all

D．trees can take in O2 and let out CO2