The correct answers are These criteria are essential for understanding the anomaly. and Much research has been conducted on this bizarre phenomenon.
"Criteria" is the plural form of the singular noun "criterion". Therefore, it must be paired with the plural demonstrative determiner "these" (not this).
"Phenomenon" is singular (plural: phenomena), so it correctly takes "this".
"Research" is an uncountable noun in English; it cannot be made plural (researches) and must be quantified with "much" rather than "many".
Noun
- The cat sat on the mat. — concrete nouns (things you can touch)
- Happiness is important. — abstract noun (idea/quality)
- London is beautiful. — proper noun (specific name, capitalised)
- I need some information. — uncountable noun (no a/an, no plural)
A noun names a person, place, thing, idea, or quality. Nouns determine article choice, verb agreement, and pronoun reference. Types: common/proper, concrete/abstract, countable/uncountable.
Test: can you put the or a before it? Can you make it plural? If yes to either → it's functioning as a noun.
Determiner
- ✅ The cat sat on a mat. — articles as determiners
- ✅ My sister has three dogs. — possessive + numeral as determiners
- ❌ I went to the home. — wrong (idiomatic: I went home — no determiner)
- ❌ She is a good student. ✅ vs She is good student. ❌ — missing determiner
A determiner sits before a noun to specify which, how many, or whose. Types include articles, demonstratives, possessives, and quantifiers.
Rule: most singular countable nouns in English require a determiner — a cat, the cat, my cat, this cat. Dropping it (cat sat on mat) breaks the sentence.
Countable and uncountable
- ✅ some advice — ❌ an advice / advices (uncountable → no article, no plural)
- ✅ a piece of furniture — ❌ a furniture / furnitures
- ✅ How much water? — ❌ How many water? (uncountable → much)
- ✅ fewer people — ❌ less people (countable plural → fewer)
English nouns are either countable (take a/an, form plurals, use many/few) or uncountable (no plural, use much/little). The choice is partly arbitrary and must be memorised.
Test: can you put a number in front? Three chairs → countable. Three furnitures ❌ → uncountable. Use a unit phrase instead: three pieces of furniture.
C1 | Advanced
- ✅ Not only did she finish early, but she also helped others. — inversion for emphasis
- ✅ It is the process that matters, not the result. — cleft sentence
- ✅ I insist that he be present. — formal subjunctive
- ✅ Were I to disagree, I would say so. — inverted conditional
These are C1 structures — the CEFR advanced level. At C1 you control inversion, cleft sentences, subjunctive forms, and register-switching fluently across formal and informal contexts.
Marker: if you can restructure a sentence for rhetorical effect without hesitation, you're C1.
Hard
- Had she not intervened, the situation would have escalated. — inverted conditional
- All distractors are grammatically plausible in other contexts
- Multiple rules interact (e.g., tense + aspect + modality)
- Context determines the answer — no single "rule" is enough
Hard marks upper-intermediate to advanced challenges: B2+, interacting rules, edge cases, plausible distractors, and contexts where pattern-matching fails.
Use "Hard" when Easy/Medium feel trivial and you want to test whether you actually understand a rule versus just recognising surface patterns.