必要条件

If high latitudes are the only requirement, couldn't you also see the auroras in Canada or Alaska?

如果高纬度是惟一的必要条件，你不是也可以在加拿大或阿拉斯加看到极光吗？

Sleep and food and water are among the biogenic needs of the organism .

睡眠、食物和水是有机体维持生命的必要条件。

Traces of surface corrosives are, however, necessary for the chem.ical reaction to take place.

少量的表面锈蚀是漆膜的化学反应发生的必要条件。

He problems of the conjugate limits and the conditions of involving as milling the helical face and the characteristic of the contact line are dusscussed.

探讨螺旋面铣削时的共轭界限、干涉等问题，得出干涉的必要条件，讨论了接触线上干涉点的特征。

Due to this technology required quantitative ore feed with stable density and nice continuity,the small sized dredge together with large sized agitation tank were employed to stope the tailing achieving excellent effect.

综述了老柞山金矿尾矿库尾矿堆存及回收有价矿物试验情况；根据浮选工艺特点及技术要求，供矿量、供矿连续性及供矿浓度的稳定是保证生产正常进行的必要条件，选择了小型采砂船与大型搅拌槽相配置的联合回采工艺，并对回采工艺特点及应用效果作了扼要介绍。

The main contents are as follows:(1) The seed dormancy types of halophytes;(2) The essential conditions for dormancy breaking of seeds in halophytes;(3) The correlation between seed germination of halophytes and salinity.

本文讨论了盐生植物种子的休眠、休眠解除及萌发的特点，主要内容有：(1)盐生植物种子的休眠类型；(2)打破盐生植物种子休眠的必要条件；(3)盐生种子萌发与土壤盐度的关系。

The reconstruction of the nation-state in Somalia is a systematic multilateral project: the ethnic reconciliation and the restoration of the domestic peace constitute the premise of its realization; the appropriate interventions offered by the international community make up a necessary condition; and the positive involvement of its neighboring countries and the organization of IGAD is also a very important factor.

索马里民族国家的重构是一项需要多边参与的系统工程，要推进索马里民族国家的重构，实现民族和解、恢复国内和平是基本前提，国际社会的合理干预是必要条件，而周边国家和伊加特组织的积极介入也是重要因素。

The contribution of modern human capital theory to economic growth theory is that it offered a satisfactory answer as to the differences of economic growth rate among countries. This theory considers that the investment on human capital and reserve of human capital is necessary to long and steady economic growth of every country because the human capital is not only ordinary production factor, but also can improve other production factors' efficiency, and can produce complementary effect to other production factor. And it can make the consume market bigger by producing themselves and re-producing themselves, thus raise economic growth rate.

现代人力资本理论对经济增长理论的贡献在于，它为认识各国经济增长率的差异提供了一个比较令人满意的解释，认为人力资本投资和积累是一国经济保持长期稳定发展的必要条件，因为人力资本不但具有一般生产要素的作用，而且也具有促使其他生产要素提高效率的功能，同时对其他生产要素具有互补效应，还可以通过自身的生产和再生产促进消费市场的扩大从而促进经济的增长。

Formation mechanism of micro-emulsion fuels is studied systematically. It isconsidered that necessary condition for biodiesel-ethanol-water micro-emulsion is thathydrogen bond effection of hydrophilic groups in biodiesel and emulsifier and hydroxyl ofethanol on water is no less than corresponding Laplace pressure gradient.

系统地研究了生物柴油-乙醇-水微乳化燃料的形成机理，认为形成生物柴油-乙醇-水微乳化燃料的必要条件是生物柴油和乳化剂所有亲水基和乙醇的羟基通过氢键作用于水的力不小于相应的拉普拉斯压力梯度。

The population inversion between the upper and lower lasing levels is considered as a necessary condition of lasing.

激光上能级和激光下能级间的粒子数反转通常被认为是实现激光振荡的必要条件。

Singer Leona Lewis and former Led Zeppelin guitarist Jimmy Page emerged as the bus transformed into a grass-covered carnival float, and the pair combined for a rendition of "Whole Lotta Love".

歌手leona刘易斯和前率领的飞艇的吉他手吉米页出现巴士转化为基层所涵盖的嘉年华花车，和一双合并为一移交&整个lotta爱&。

This is Kate, and that's Erin.

这是凯特，那个是爱朗。