推动因素与原产地有关。
In general, pull factors add up to an apparently better chance for a good life and material well-being than is offered by the place of origin.一般来说,促使因素叠加显然比原产地提供的条件更易获得良好的生活和物质福利。
Mature butterflies retain the glycosides in a mature monarch butterfly could be used to determine its place of origin.成熟的蝴蝶在成熟的黑脉金斑蝶体内保留糖苷,可以用来确定其产地。