billion years ago中文是什么意思

• 亿年前

• billion     several billions of pe ...
• year    n. 1.年，岁；一年。 2.年度，学年。 3.〔pl. ...
• ago    adv. 以前，前。 ten years ago 十年前 ...
• billion years    十亿年
• years ago    多年前
• billion losses over years    三年中亏损180亿
• years before=many years ago    几年前
• a few years ago    几年前
• a thousand years ago    一千多年前
• all those years ago    多年以前
• christmas years ago    三百年前的圣诞节
• five years ago    五年前; 五年之前
• hundreds of years ago    几百年前
• i was here years ago    很多年前我来过这
• it happened thirty years ago    这事出在30年前
• just a few years ago    只不过几年前
• many years ago    许多年前
• no mystery three years ago    三年早知道
• only a few years ago    只不过几年前
• perhaps three years ago    也许在三年前
• scores of years ago    许多年前
• since many years ago    多年来
• that was twenty years ago    距今已有二十年
• thousands of years ago    数千年前
• three years ago    大前年

• At some time more than five billion years ago the universe started .
  在50亿年前的某个时候，宇宙开始形成。
• Yet oxygen gas did not begin to accumulate in the atmosphere until about 2 billion years ago .
  但是大约在20亿年前，氧气才开始在大气层中积累。
• The organisms living between 3 and 1 billion years ago were not as versatile as modern species, probably due to energy limitation .
  生活在过去二十亿年之间的有机体可能由于能量的限制，不如现代物种这样五花八门。
• Our solar system was formed 4 . 6 billion years ago
  我们的太阳系被形成了4 . 6十亿年前。
• The supernovae exploded between 3 . 5 and 10 billion years ago
  超新星爆炸时间在35 - 100亿年前。
• What prompted the leap in complexity starting 1 . 5 billion years ago
  那么是什么推动了发生在15亿年前的复杂性的飞跃呢？
• About 5 billion years ago
  五十亿年以前
• About 13 . 7 billion years ago a tremendous explosion started the expansion of the universe
  大约13 . 7十亿年前巨大爆炸开始了宇宙的扩展。
• Just as the solar system was forming some 4 . 6 billion years ago , it turned itself inside out
  太阳系的形成发生在大约46亿年前，那会儿它里外翻了个身。
• For example , the researchers date the split between plants and animals at 1 . 6 billion years ago
  例如，研究者确定植物和动物大概是在16亿年前开始产生差异。