

step by step(初级刀客调整)
step:回顾单词(再熟悉熟悉,搞好关系撒)
: Q4 e* E9 B# X9 m( Y% Pstep:总结185篇的一篇
2 d% T- P8 p+ V8 u5 S0 v% Cstep:听写&跟读(不容易啊,总算是回来了)% ^5 A; L8 {' X2 \6 j$ R( y0 W
step:阅读longman
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; D5 N/ j) n# P% i, X3 V8 e. {+ d3 C0 y第四篇(地质类)
: M9 j( v$ t" G; r7 N+ [I often hear my friends say that days pass more quickly than they used to. But geologically speaking just the opposit is true. In fact, a complete day which now last 24 hours actually used much shorter only about 18. How do we know that? because of the number of finally strata rocks like this. Rock form belong ancient shorelines almost billion years ago. The tiny lines of these samples show us layer of light and dark formed by dust blow over the shoreline from the landsite. Alternating was the mud and sand desposited by the waves. So the space betwennone dark strata and the next emphases of the time between on month high tide and the next. And very in fitness of layer show us the circle of the season as well. Together the data indicate there were fewer months for year way back then. That means the Moon was moving more slowly than as it revovlved around the earth. So what caused the moon do speed up so much over last billion years. It must be the tides. Think about it as the gravity of moon pulls on the oceans to form the tides. all that water is also pulling on the moon and with each rotation it makes the moon move a tiny bit faster. At the same time, like the brakes on the wheel of bicycle, the drag caused by the moon's gravity makes the earth turn just a tiny bit slower. And so after a billion years, one rotation meaning one day takes a lot longer than it once did