I need it as soon as possible.

as 在这里是连词，表示"像...一样"或"当...时"。 soon 是副词，意思是"不久、很快"。 as possible 中的 as 是副词，表示"同样地"；possible 是形容词，意思是"可能的"。 as soon as possible 是一个固定短语，字面意思是"像尽快那样快"，通常简称为"尽快"，英文缩写为ASAP。