碘是紫黑色晶体,可以溶解在汽油中,形成紫红色溶液.
“黑火药”是我国古代四大发明之一,它由硝酸钾、硫磺、木炭组成。“黑火药”属于 ( )
Who
With whom
Where to go
What to do
My father
Mr Green: ____
France
Go ____
My mother
Mrs Brown: Patient
____
Go shopping and
My sister
Linda: Smart
The US
Visit ____
1÷5=____ 4÷12-=____
某滩涂是丹顶鹤的栖息地之一,在该滩涂建立丹顶鹤自然保护区的主要目的是