billion years meaning in English
十亿年
Examples
- It has a half-life of about 41/2 billion years .
它的半衰期大约为45亿年。 - 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。 - The youngest rocks found on the moon are 3 billion years old .
在月球上发现的地质年代最晚的岩石已有30亿年历史了。 - Their ancestors have been eating according to flavor for upwards of a billion years .
他们的祖先已经根据滋味来吃东西吃了十亿年以上了。 - 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。