A:①②
B:③④
C:①③
D:②④
-- Where are the trees? -- They are beside the r____.
They are looking forward to an exciting vacation.
某电镀厂排出的废水中含有较多的硫酸铜(CuSO4)。若要从硫酸铜中获得金属铜,以减少废水对环境的污染,可选择下列物质中的( )
生物的多样性不包括( )