阅读下面短文，根据所给情节进行续写，使之构成一个完整的故事。

Itwasacoolfallmorning,andthesunwasjuststartingtorise,castingawarmlighttothequietneighborhood.ForAlex,thehighschooljuniorwithadeeppassionforscience,wasfilledwithbothexcitementandnervousness.Todaymarkedthefinalpresentationof