hãy tính số mol của :

a. 5g silver

b. 7g khí nitrogen

When the temperature rises, the ice begins to …………..…… 

A. freeze        B. melt        C. evaporate        D. disappear

A ………….is a kind of black and bird which can’t fly but uses their wings to swim.

    A. polar bear    B. blue whale    C. penguin    D. dolphin

We should …………..……. drink cans and used paper to save the environment.

a.reduce        B. throw away    C. burn        D. recycle 

We shouldn’t …………..……. electricity so we can reduce pollution.

a.waste        B. save        C. use             D. reuse

We should help clean rivers and beaches so we can …………..…… water pollution.

a.reuse         B. reduce        C. recycle        D. damage

…....................... is a natural environment in which a kind of animal or plant lives.

a.Space        B. Habitat        C. Zoo        D. Park 

………………… is a long period of time when there is little or no rain.

a.Flood        B. Storm        C. Acid rain        D. Drought

……………………is the average height of sea where it meets the land.

A. Sea level        B. Sea range        C. Seaside         D. Sea shore

My mother raises some chickens and they lay many …………………..

A. babies        B. eggs        C. children        D. kids

  We should   turn ……………… lights after class to save electricity.

A. on            B. up            C. off            D. down

Pollution will………………… people and wildlife.

    A. affects    B. effect    C. affect    D. effects

Eating fruits and vegetables is good ………………… your health.

    A. at    B. in    C. to    D. for

I’m scared the trees will fall and ………………… our house.

    A. burn    B. damage    C. pollute    D. cause

………………… is a change in weather that makes the Earth hotter or colder.

    A. pollution    B. wildlife    C. climate change             D. tourism

………………… is both plants and animals in nature.

    A. wildlife    B. pollution    C. environment    D. disease

II. WRITING:

lights from/ I think/ light pollution/ are causing/ buildings/.

          I think……………………………………………………………………………………

the food/ If we keep/ that we grow/ it will/ polluting the land, / affect/.

          If we …………………………………………………………………………………….

air pollution/ transportation/ use public/ reduce/ We should/ so we can/.

          We should……………………………………………………………………………….

to grow/ will make/ plants and trees/ The hotter weather/ it difficult for/.

          The hotter weather ……………………………………………………………………...

throw trash/ can reduce/ We shouldn’t/ water pollution/ into rivers/so we/.

          We shouldn’t ………………………………………………………………………….

Don’t litter the place around you or it will be a junk yard.

           If…………………………………………………………………………………

Reduce the use of energy or you’ll pay more for it.

            If…………………………………………………………………………………

Don’t be careless or you will break the vase

           If……………………………………………………………………………………

Stop polluting the air or the effects of climate change will be worse.

          If……………………………………………………………………………………