18-lightening gives life

Listen and fill in the blanks with proper words.

1. Lightning strikes during Earth’s early_______ helped make phosphorus.

2. Phosphorus not only helps make _______ andRNA, but also gives ________ to cells.

3. Scientists say that about 4 billion yearsago, most of Earth’s phosphorus was in ______.

4. Scientists believe that in early times, therewere about _____ billion to 5 billion lightning strikes each year on Earth.

Lightning gives life

How did life on Earth begin? Maybe it began witha lightning strike (一道闪电). 

According to a new study by Yale University,lightning strikes during Earth’s early history helped make phosphorus (磷). It is important for life. Phosphorus not only helps makeDNA and RNA, but also gives energy (能量) tocells (细胞). You can also find phosphorus in bones andteeth.
Scientists say that about 4 billion (十亿) years ago, most of Earth’s phosphorus was in rocks.However, when lightning hit these rocks, it changed them and made them dissolve(溶解) in water. The phosphorus then came out of therocks.
Scientists believe that in early times, there wereabout 1 billion to 5 billion lightning strikes each year on Earth. This meansthat 4.5 billion and 3.5 billion years ago, lightning strikes created 110 to11,000 kg of phosphorus every year!
So next time you’re asked, “Where did you comefrom?”, you could say, “A lightning strike!”