The history of the tortoise
Walter Joyce and Jacques Gauthier, at Yale University, obtained three measurements in these particular bones of 71 species of living turtles and tortoises. They used a kind of triangular graph paper to plot the three measurements against one another. All the land tortoise species formed a tight cluster of points in the upper part of the triangle; all the water turtles cluster in the lower part of the triangular graph. There was no overlap, except when they added some species that spend time both in water and on land. Sure enough, these amphibious species show up on the triangular graph approximately half way between the 'wet cluster' of sea turtles and the 'dry cluster' of land tortoises. The next step was to determine where the fossils fell. The bones of P. quenstedti and P. talampayensis leave us in no doubt. Their points on the graph are right in the thick of the dry cluster. Both these fossils were dry-land tortoises. They come from the era before our turtles returned to the water.
determine, ascertain, discover, learn, unearth
這組詞都可表示「發現以前自己不知道的東西」。其區別是：
determine：強調尋找事實或真理,以解決爭端或爭執，主要用於科學和法律方面。
ascertain：很少指偶然的發現，側重先前的無知與無把握，以及認真地去發現真理或真相。
discover：指經過調查、探索去發現已經存在或可能存在、事實上的東西，這種發現也可能出於偶然。
learn：指獲得知識,發現者一般沒有或很少花多大力氣。
unearth：指將隱藏的、被遺忘的、失去的或極其難以追尋的東西公之於眾或暴露於世，常常強調發現以前所做的認真長期的調查。
determine, decide, fix, make up one's mind, resolve, settle
這組詞都有「決定」的意思。其區別在於：
determine：強調「意志堅定、不可動搖」，也常用於科技方面通過調查或認真思考後作出「決定」或「確定」。
decide：側重指經過思考、比較、討論或詢問之後做出的決定。
fix：指經過考慮和商議後作出決定,強調不再改變。
make up one's mind：指下決心做某事,不再改變。
resolve：語氣較強，強調以堅定不移的信念去做或不做某事，暗含有遠大抱負和堅強決心。
settle：指排除猶豫、懷疑和爭論之後作出明確的最終結論。