阅读下面短文，从短文后所给的[A]、[B]、[C]三个选项中选出能填入空白处的最佳选项。

issAC nEwton wAs A FAmous sCiEntist (科学家). hE{{u}} (41) {{/u}}A-Bout thE lAws oF nAturE (自然界，本性){{u}} (42) {{/u}}thAn Any othEr sCiEntist in his timE. hE lEArnED By looking ClosEly At things AnD By{{u}} (43) {{/u}}hArD、hE wAs AlwAys in DEEp{{u}} (44) {{/u}}. {{u}} (45) {{/u}}hE wAs A wisE (聪明的，明智的) sCiEntist, hE FElt thAt hE wAs nEvEr too olD to lEArn. hE thought (想) thAt whAt hE knEw wAs likE A Drop (滴) oF knowlEDgE (知识，知道){{u}} (46) {{/u}}. hE Also sAiD, "mAn shoulD not AmusE (逗乐){{u}} (47) {{/u}}By FinDing A smooth (平滑的) pEBBlE (鹅卵石) or prEtty (漂亮的，相当) shEll (外壳，泡弹){{u}} (48) {{/u}}A Boy DoEs. hE must lEArn morE By swimming{{u}} (49) {{/u}}thE sEA、" thE morE you lEArn, thE morE thErE is{{u}} (50) {{/u}}to BE lEArnED、

A．

[A] think

B．

[B] thinking

C、

[C] thought