山东省教育招生考试院官网
山东省教育招生考试院官网
![眼镜店加盟 眼镜店加盟](https://huanqiudh.com/zdmsl_include/images/error.png)
TherehasbeenlifeonEarthforaround3.5billionyears.Thefirstmicroscopicsingle-celledorganismsresidedintheworld’soceansandgraduallydevelopedintocomplex,multicellularorganisms,fromdinosaursinthebeginningtomammalsasweknowthemtoday.Thiswasaresultofevolution,whichisdrivenbynaturalselection:onlylivingthingsthatsuccessfullyadapttotheirenvironmentwillsurvive.