When plants pioneered the land, they faced a range of challenges posed by terrestrial environments.
当植物开辟土地时，它们面临着陆地环境带来的一系列挑战。
But that makes it easier to identify something as a meteorite, as opposed to just a terrestrial rock.
但是，这使得我们更容易将东西识别为陨石，而不仅是地面的岩石。
This obliquity creates the terrestrial seasonality so important to the evolution and diversity of life.
这种倾斜创造了对生命进化和多样性如此重要的陆地季节性。
The polar bear is the largest terrestrial carnivore, being more than twice as big as the Siberian Tiger!
北极熊是陆地上最大的肉食性动物，比西伯利亚虎都要大两倍多！
The other islands, which emerged via geological processes such as volcanism, possessed no terrestrial life.
其他岛屿是通过如火山作用的地质作用形成的，没有陆地生命。
Even diluted by the terrestrial material excavated from the crater, this component of meteorites is easily identified.
即使被从陨石坑中挖掘出的陆地物质稀释，这种陨石成分也很容易识别。
Although most fossils are found in marine sedimentary rocks, they also are found in terrestrial deposits left by streams and lakes.
虽然大多数化石是在海洋沉积岩中发现的，但它们也存在于河流和湖泊所留下的陆地沉积物中。
The average density of interstellar material in the vicinity of our Sun is 1,000 to 10,000 times less than the best terrestrial laboratory vacuum.
在我们的太阳附近，星际物质的平均密度比最好的地球实验室真空还要低1000到10000倍。
Once natural selection had shaped the adaptations that helped plants overcome the obstacles to terrestrial living, plants prospered and diversified.
一旦自然选择塑造了植物的适应机制，使之克服在陆地生活的障碍，植物物种就生机勃勃且丰富多样了。
Some researchers have argued that speciation rates, both terrestrial and marine, could be much higher in the tropics, making them a "cradle" of biodiversity.
一些专家认为，在热带地区的陆地和海域，物种形成的机率更高，这样就使热带地区成为了生物多样性的摇篮。
Whales and dolphins have been found with hind limbs; this rare occurrence is due to the reemergence of a trait they inherited from their terrestrial ancestors.
发现鲸和海豚身上有后肢；这种稀有的现象是由于它们在陆地上的祖先身上的特征再次被遗传。
Nevertheless, a good number of thoroughgoing land animals later turned around, abandoned their hard-earned terrestrial re-tooling, and returned to the water again.
尽管如此，后来还是有相当数量的完全陆生动物做出改变，离开了它们辛辛苦苦重新改造的陆地，并回到了水里。
One option for moving toward both biodiversity and terrestrial food supply goals is to produce greater yields from less land, thereby freeing land for conservation purposes.
实现生物多样性和陆地食物供应目标的一种选择是用更少的土地生产更高的产量，从而腾出土地用于保护目的。
Moreover, materials that have transitions at the temperatures that terrestrial solar-energy systems are likely to encounter are usually destructively corrosive at those temperatures.
此外，在地球太阳能系统可能遇到的温度下发生转变的材料在这种温度下通常具有破坏性的腐蚀性。
These rocky planets are called "Terrestrial Planets".
这些岩态行星被称为“类地行星”。
The gills of fishes are analogous to the lungs in terrestrial animals.
鱼类的鳃与陆上动物的肺类似。
By comparison, the terrestrial planets have meager atmospheres at best.
相比之下，类地行星最多只有稀薄的大气层。
The interstellar material, rather like terrestrial clouds, comes in all shapes and sizes.
星际物质很像地球上的云，形状大小各异。
However, unlike Jupiter, the terrestrial planets today are nearly void of light gases and ices.
然而，如今的类地行星与木星不同，几乎没有轻气体和冰。
The terrestrial planets are mostly rocks: dense rocky and metallic material, with minor amounts of gases.
类地行星主要是岩石：密度大的石块和金属物质，同时会有少量的气体。
These asteroids are like the terrestrial planets, in that they're composed mostly of rocky material and metals.
这些小行星像类地行星一样，主要由岩石物质和金属构成。
Other adaptations occurred later in the transition to terrestrial life and now wide spread but not universal among plants.
其他的适应机制在向陆地过渡过程中出现得较晚，现在在很多植物上得以呈现，但并不是所有的植物都如此。
Also, because of their relative locations, the four Jovian planets are known as the outer planets, while the terrestrial planets are known as the inner planets.
同样，由于它们的相对位置，四颗类木行星被称为外行星，而类地行星被称为内行星。
Constant variations in the amount of sunlight available on Earth at any given location make energy storage a necessary design feature of terrestrial solar-energy systems.
在地球上任何一个特定地点，阳光的不断变化使能量储存成为地球太阳能系统的一个必要设计特征。
The densities of the terrestrial planets average about 5 times the density of water, whereas the Jovian planets have densities that average only 1.5 times the density of water.
类地行星的密度的平均值大约是水的密度的五倍，而类木行星的密度平均值只有水的密度的1.5倍。
The largest terrestrial planet, Earth has a diameter only one quarter as great as the diameter of the smallest Jovian planet, Neptune, and its mass is only one seventeenth as great.
最大的类地行星地球的直径仅仅是最小的类木行星海王星的四分之一，而且地球的质量仅仅是其质量的十七分之一。
The scale of the searches has been increased dramatically since 1992, when the US Congress voted NASA $10 million per year for ten years to conduct a thorough search for extra-terrestrial life.
自1992年，美国国会计划在未来10年里每年为美国国家航空航天局投入1,000万美元，用于彻底搜寻外星生命体以来，搜寻的规模开始大幅增长。
The scale of the searches has been increased dramatically since 1992, when the US Congress voted NASA $10 million per year for ten years to conduct a thorough search for extra-terrestrial life.
自1992年，美国国会计划在未来10年里每年为美国国家航空航天局投入1,000万美元，用于彻底搜寻外星生命体以来，搜寻的规模开始大幅增长。
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