過去式：ascertained 過去分詞：ascertained 現在分詞：ascertaining
你對啦! ascertain的確是動詞 這句話可以改成 1. We couldn't determine whether... 2. We were unable to ascertain whether... 3. We were unable to ascertain the authorship of the reports...
察言觀色↓ 1.Ascertain intent through word and express 詩情畫意↓ 2.The poetry painting idea...
...the phenotypic monitoring of defined flower genotypes and to ascertain the diffusion and use of transgenic cultivars in the envionment... 其即時檢測...