Before publishing the research, the scientists needed to ascertain the exact composition of the mineral sample.
在发表研究之前，科学家们需要查明矿物样本的确切成分。
Which choice best defines “ascertain”?
D — Determine; find out; establish. “ascertain” means determine; find out; establish.
Which word means “determine; find out; establish”?
C — ascertain. “ascertain” means determine; find out; establish.
ascertain — determine; find out; establish. In Chinese: 查明；确定.
ascertain is pronounced /ˌæsərˈteɪn/.
Before publishing the research, the scientists needed to ascertain the exact composition of the mineral sample. (在发表研究之前，科学家们需要查明矿物样本的确切成分。)
determine, verify, establish — all close in meaning to ascertain (determine; find out; establish).
overlook, guess — each the opposite of ascertain (determine; find out; establish).
Yes. ascertain is on the SAT Prep Difficult list — the higher-register words that decide the hard questions. The Digital SAT does not test vocabulary in isolation; words like this one are tested through Words in Context questions, where you choose the word that completes a passage most logically and precisely.
as-(strengthen) + certain (confirm) → to ascertain, confirm.