Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

[Q]: Sentence1: sharpening an object causes that object to change shape. 
Sentence2: sharpening a knife causes it to change shape.
[A]: causes


[Q]: Sentence1: Average vehicle speed rises by only 0.3 miles per hour. 
Sentence2: a speedometer measures miles per hour.
[A]: hour


[Q]: Sentence1: Ducks generally have webbing on their feet. 
Sentence2: Ducks can move fast through water.
[A]:
Ducks