不挂科搜题免费

问题:

Which is available to plants for use?

选项

  • ammonia (氨, 氨水)

  • nitrate (硝酸盐, 硝酸钾)

  • nitrite (亚硝酸盐)

  • nitrogen(氮) gas

  • 答案:

    B.nitrate (硝酸盐, 硝酸钾)