The hypothesis remained too nebulous to test until someone specified what would count as evidence against it.
在有人明确指出什么算作反面证据之前，这一假说一直模糊到无法检验。
Which choice best defines “nebulous”?
D — Vague; ill-defined.. “nebulous” means Vague; ill-defined..
Which word means “Vague; ill-defined.”?
D — nebulous. “nebulous” means Vague; ill-defined..
nebulous — Vague; ill-defined.. In Chinese: 模糊的；含糊的.
nebulous is pronounced //ˈnɛbjələs//.
The hypothesis remained too nebulous to test until someone specified what would count as evidence against it. (在有人明确指出什么算作反面证据之前，这一假说一直模糊到无法检验。)
vague, hazy, indistinct — all close in meaning to nebulous (Vague; ill-defined.).
precise, definite — each the opposite of nebulous (Vague; ill-defined.).
Yes. nebulous 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.
nebul(云雾) → 云里雾里。