Gōngchéngshī / zhèngzài / cèshì / xiàngjiāo / de / shēnsuōxìng / yǐ / quèbǎo / chǎnpǐn / ānquán工程师正在测试橡胶的伸缩性,以确保产品安全。The engineers are testing the rubber's elasticity to ensure product safety.