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: a stopwatch is used to measure time. 
Sentence2: Time can be measured with a clock or watch.
[A]: measure


[Q]: Sentence1: a circle graph can be used to display percents. 
Sentence2: pie charts are circle graphs.
[A]: circle


[Q]: Sentence1: Smog contains particulates. 
Sentence2: Particulate matter varies in size.
[A]:
particulates