Help the mad scientist finalize his evil laboratory report.
"The new potion will ___ the town's water supply, creating a disastrous ___ on everyone's hair color."
The correct answer is affect / effect.
Affect is almost always a verb meaning "to influence or change" (The potion will affect the water).
Effect is almost always a noun meaning "the result of a change" (creating a disastrous effect).
Helpful trick: Think of the acronym RAVEN: Remember Affect Verb, Effect Noun.
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.
Noun
Noun vs verb: the two core word classes. Nouns name things; verbs describe actions/states. Many English words can be both (run, play, cook, work) — only the sentence slot tells you which role it's playing. The run was exhausting (noun) vs I run every day (verb).
A noun names an entity. It interacts with articles, determiners, forms plurals, and controls verb agreement and pronoun choice.
Diagnostic: can you put the/a before it or pluralise it? → noun. Does it describe an action with tense? → verb. Can it do both? → check the sentence context.
Future tense
Will vs going to: the most confused future pair. Will = spontaneous decisions and predictions (I'll have the fish; It will rain). Going to = pre-existing plans and evidence-based predictions (I'm going to study law; Look at those clouds — it's going to rain). Swap them and you sound either impulsive or weirdly formal.
English encodes future time through will, be going to, present continuous (arrangements), and present simple (schedules) — each with different implications.
Diagnostic: is the decision happening right now? → will. Was it already planned? → going to. Is it a confirmed arrangement with another person? → present continuous.
B2 | Upper Intermediate
B2 vs C1: B2 means effective communication on complex topics with some effort. C1 means effortless fluency with precise register control. If you can argue a point but still reach for words and make structural slips under pressure, you're B2.
B2 is the upper-intermediate CEFR level: mixed conditionals, complex passives, reported speech with backshift, participle clauses, and sustained written argument.
Diagnostic: does your writing read as "competent non-native" or "could be native"? The former → B2. The latter → C1.
Medium
Medium vs Easy: Easy has one obviously correct answer and clearly wrong distractors. Medium has one correct answer but plausible distractors — you need to actually know the rule, not just guess from sound.
The Medium tag filters for A2–B1 challenges with realistic difficulty: one rule per question, plausible alternatives, everyday contexts.
Diagnostic: if you're scoring 90%+ on Easy, move here. If you're below 60% on Medium, go back to Easy for that topic. Target 70–80% accuracy for maximum learning.