Help Dr. Von Quark finalize the safety protocols for his new time machine by dragging the correct verb forms into the gaps.
It is imperative that the temporal capacitor remain completely submerged in pickle juice.
I strongly recommend that my assistant, Igor, be wearing his lead underwear when the countdown begins.
Furthermore, I dictate that the dimensional portal not be opened until after lunch.
It is imperative that the temporal capacitor remain completely submerged in pickle juice.
Adjectives expressing urgency or necessity (like "imperative") trigger the subjunctive in the following that-clause. We use the base form of the verb ("remain") without an "-s".
I strongly recommend that my assistant, Igor, be wearing his lead underwear when the countdown begins.
Verbs of recommending trigger the subjunctive. Here, we need the continuous subjunctive form, which is "be" + present participle ("be wearing").
Furthermore, I dictate that the dimensional portal not be opened until after lunch.
This gap requires both the negative and passive subjunctive. We place "not" before the base form "be", followed by the past participle "opened".
Subjunctive mood
Subjunctive vs indicative: indicative states facts (He goes every day). Subjunctive marks unreality (I suggest he go; If I were you). The subjunctive drops the -s and insists on were — signalling "this isn't (or may not be) real." In informal speech it's disappearing, but formal/academic writing still expects it.
The subjunctive mood = hypothetical/counterfactual marker. Present subjunctive (base form after suggest/demand/insist that). Past subjunctive (were in unreal conditionals).
Diagnostic: is the clause about something unreal, demanded, or recommended (not yet true)? → subjunctive. Is it factual? → indicative.
Passive voice
Active vs passive: active puts the doer first (The dog bit the man). Passive puts the receiver first (The man was bitten by the dog). Neither is inherently wrong — choice depends on what you want to foreground. Scientific/formal writing uses passive deliberately; vague writing uses it accidentally.
Passive voice = be + past participle. Promotes the object to subject. Good for foregrounding the action/result; bad when it hides who's responsible.
Diagnostic: who's doing the action? If unnamed and that matters → bad passive. If unnamed because it's obvious or irrelevant (The building was constructed in 1920) → good passive.
Clause
Clause vs phrase: a clause has a subject + verb (she runs); a phrase does not (in the morning, running fast). This is the first distinction to make when analysing sentence structure.
A clause is a grammatical unit built around a verb: independent clauses make complete sentences; dependent clauses attach to them as modifiers or complements.
Diagnostic: find the verb. If there's a subject doing or being something → clause. If there's no subject-verb pair → phrase.
Negation
Single vs double negatives: standard English uses ONE negative per clause (I don't see anything or I see nothing). Double negatives (I don't see nothing) are grammatical in many languages and some English dialects, but are non-standard in written/formal English. This is the #1 negation trap for speakers of Spanish, Russian, and French.
Negation = not after auxiliary/modal, or do-support. Negative words (never, nobody, nothing) negate alone without adding not.
Diagnostic: count the negatives in the clause. More than one? → double negative. Fix by replacing one with a positive (anything, anyone, ever).
Verb
Verb vs noun vs adjective: nouns name things. Adjectives describe. Verbs express what happens or what IS. The test: can it take tense (walked, will walk)? Can it take -ing? Can it follow to as an infinitive (to walk)? Yes to any → verb. English often converts freely between classes (run = noun or verb), so context decides.
A verb = action/state/occurrence word. 5 forms (base, -s, past, past participle, -ing). Carries tense, aspect, mood, voice. The one required element in every sentence.
Diagnostic: does it change for tense (walk → walked)? Can you put to before it (to walk)? Does it take -ing (walking)? → verb.
C1 | Advanced
C1 vs C2: C1 means fluent and flexible use with occasional gaps in very unfamiliar domains. C2 means native-like command of idiom, irony, and register across any subject. If you can handle advanced grammar but still miss cultural nuance or very rare idioms, you're C1.
C1 is the advanced CEFR level: inversion, cleft sentences, subjunctive mood, advanced conditionals, and precise register control in professional and academic contexts.
Diagnostic: can you write persuasively in different registers and catch subtle irony? Consistently → C2. Sometimes → C1.
Hard
Hard vs Medium: Medium tests one rule with realistic distractors. Hard tests interacting rules, edge cases, or context-dependent answers where multiple options seem correct until you think deeply. If you're scoring 80%+ on Medium, try Hard to find your real gaps.
The Hard tag filters for B2+ challenges with layered difficulty: rule interactions, subtle distractors, and contexts that demand genuine grammatical reasoning.
Diagnostic: if Hard questions feel impossible, drop to Medium and master the individual rules first. Hard assumes you already know each rule — it tests whether you can apply them together.