Damage was done. It was unclear who will pay for it.
Make a complex sentence.
Who was going to pay for the damage was unclear.
Who was going to pay for the damage was unclear.
This is an example of a relative clause starting with who: It functions as a subject - It is unclear.
Independent clause
Independent vs dependent clause: both have subject + verb. The difference: independent clauses express a complete thought and stand alone. Dependent clauses start with a subordinator (because, if, who) and can't stand alone. Every sentence needs at least one independent clause.
An independent clause = subject + verb + complete thought. Sentence = one or more independent clauses (optionally with dependent clauses attached).
Diagnostic: can this group of words be a sentence on its own without feeling incomplete? Yes → independent clause. No → dependent or fragment.
Dependent clause
Dependent vs independent clause: an independent clause stands alone as a sentence (I was tired.). A dependent clause has a subject + verb but cannot stand alone (Because I was tired. ❌). The subordinating word is what makes it dependent — remove it and the clause becomes independent.
A dependent clause is introduced by a subordinating conjunction or relative pronoun and functions as an adverb, adjective, or noun inside a larger sentence.
Diagnostic: strip the opening word (because, if, who, which). Does the remainder work as a sentence? Yes → the original was dependent (the subordinator trapped it). No → deeper structural issue.
Complex sentence
Complex vs compound sentence: a compound sentence links two equal independent clauses with and/but/or. A complex sentence links an independent clause with a subordinate (dependent) clause — one idea is the main point, the other is background.
A complex sentence = independent clause + dependent clause. The dependent clause adds time (when), reason (because), condition (if), or detail (who/which).
Diagnostic: are both halves able to stand alone? Yes → compound. Can only one stand alone? → complex.
B1 | Intermediate
B1 vs B2: B1 handles standard everyday communication and simple opinions. B2 handles abstract topics, sustained arguments, and nuanced register. If you can chat about your life but struggle to debate an issue or write a formal essay, you're B1.
B1 is the intermediate CEFR level: independent handling of familiar topics, second conditional, basic passive, reported speech, and linking words for cause and contrast.
Diagnostic: can you read a newspaper article on a familiar topic and summarise the argument? Comfortably → B2. Struggle with abstractions → still B1.
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.