In 1862, building of a railroad to join the pacific coast with the mississippi river valley was begun . 一八六二年，一条连结太平洋海岸与密西西比河流域的铁路开始修建。
It permits a population to spread as the population increases, and it enables the colonization of new sites . 它使得种群在其增长的时候得以扩展它的分布区域并移居到新的场所。
Molecular orbitals describe the location of electrons in a molecular environment under the influence of more than one nucleus . 分子轨道可用来描述分子中在多个核作用之下电子定域情况。
By translations and changes of scale the spectral subspaces associated with all discs can be characterized similarly . 通过平移与尺度改变，伴随着一切圆域的谱子空间都可以类似地给予刻划。
The creation of the concept of the definite integral was motivated by the problem of calculating the areas of certain plane regions . 定积分概念的产生是由求一个平面域的面积问题而导致的。
These stray currents usually have a higher frequency (50-60h2 harmonics) than those used in the ip frequency technique . 这些游散电流的频率（5060H2及其谐波）通常比IP频率域法中用的频率要高。
The stippled area shows the distribution of a clean, permeable sandstone in the lower part of the lower cretaceous muddy formation . 图上画点部分为下白垩纪马迪组下部洁净，渗透的砂岩分布区域。
The association chain implied is general reactivity, delocalization, heat of reaction, activation energy, velocity constant . 和该量有牵连的因素是一般活性，离域作用，反应热，活化能，速度常数。
I feel like one who was toiling home barefoot from distant travel, and whose wanderings had lasted many years . 我觉得自己象是个异乡绝域漂泊多年的人，如今光着脚板，涉水跋山，千里迢迢地归来了。
These conditions should be appreciated when considering estimates of neighborhood size for forest trees given in the literature . 当参考文献中所给的林木邻域大小估计量时，这些情况都应当予以考虑。
