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: Asbestos is a dangerous carcinogen. 
Sentence2: Asbestos causes cancer.
[A]: Asbestos


[Q]: Sentence1: Secondary accidents are a major problem under driving conditions of reduced visibility. 
Sentence2: Bad weather increases the risk of car accidents.
[A]: Secondary


[Q]: Sentence1: Sporangia produce spores that develop into tiny, heart-shaped gametophytes. 
Sentence2: Gametophytes of extant genera are green, photosynthetic,and have a long ribbon shaped thallus.
[A]:
heart-shaped