Tā / de / yán / jiū / bù / jǐn / jiě / jué / le / shí / jì / wèn / tí / yě / jù / yǒu / yí / dìng / de / lǐ / lùn / gòng / xiàn

他的研究不仅解决了实际问题，也具有一定的理论贡献。

His research not only solves a practical problem but also makes a certain theoretical contribution.