【正确答案】 1、G    

【答案解析】[精析] 空白处下文的"In other words"表明下文是对空白处的进一步解释，二者意思应该相近。下文提到了“course corrections”E、C项都与此有关。但E项中的第二句话"This would have been possible in theory，but we know that Columbus could not have actually done this．"与下文意思不符。而G项则与下文意思相近，故G项正确。