The correct answers are It's obvious that the robot dog lost its favorite titanium bone. and The company announced that it's recalling the model because of its faulty tail.
It's is a contraction for "it is" or "it has."
Its is a possessive word meaning "belonging to it" (just like "his" or "hers").
Native speakers often add an apostrophe to "its" by mistake, forgetting that possessive pronouns (like his, hers, ours, yours, its) never take an apostrophe!
Pronoun
A pronoun is a small, closed class of words that stands in for a noun or noun phrase. The main types: personal (I, you, he, she, it, we, they) plus their object (me, him) and possessive (my, mine) forms; demonstrative (this, that); relative (who, which, that); interrogative (who, what); and reflexive (myself, yourself).
Pronouns are how English avoids endlessly repeating names. The catch: their meaning depends entirely on context, so unclear pronoun reference (Tom told Mike that he was wrong — who's he?) is one of the most common writing problems.
Possessive
The possessive form shows ownership or association in English. With most nouns, you add 's (Sarah's book, the dog's tail); with plural nouns ending in s, you add just an apostrophe (the students' essays). Pronouns have irregular possessives — both possessive determiners (my, your, his, her, our, their) and possessive pronouns (mine, yours, his, hers, ours, theirs).
The most-mixed-up pair: its (possessive of it) vs it's (= it is). Possessive its takes no apostrophe; it's always means it is or it has. Getting this right is one of the highest-leverage punctuation moves in English.
Apostrophe
The apostrophe ( ' ) is a punctuation mark with two main jobs in English: marking missing letters in contractions (do not → don't, they are → they're) and showing possession with nouns (the eagle's feathers, one month's time). It's not used for plurals — cats never takes an apostrophe, even though many writers slip and add one.
Mixing up its (possessive) and it's (contraction of it is), or writing banana's £1 on a market sign, are the giveaway errors that mark a writer as careless. Getting the apostrophe right is one of the highest-leverage punctuation skills you can learn.
Punctuation
Punctuation is the set of visual marks — periods, commas, question marks, colons, semicolons, apostrophes, quotation marks, hyphens and dashes — that show readers where sentences begin and end, where pauses go, and how parts of a sentence relate.
Punctuation does two jobs: it follows the rhythm of speech (where you'd pause aloud) and it marks the structure of clauses. Mismatch the two and writing reads either as breathless or as choppy. Mastering the basics is a small investment with huge returns — clear punctuation makes prose look careful and considered.
Determiner
A determiner is a word that comes before a noun to clarify what it refers to: which one, how many, whose. The English determiners include articles (a, the), demonstratives (this, that), possessives (my, your), quantifiers (some, many, few), and distributives (each, every).
Most singular countable nouns in English require a determiner — I bought book is wrong; you need I bought a book or I bought the book. Determiner choice signals how much information you assume the listener already has, so getting it right shapes how natural your speech and writing sound.
B2 | Upper Intermediate
B2 is the upper-intermediate level in the CEFR framework, sitting between B1 and C1. At B2 you can read editorials, follow most TED talks without subtitles, and hold extended conversations on abstract topics — including topics outside your everyday life.
Grammatically, B2 means flexible control of mixed conditionals, passive voice across tenses, reported speech with proper backshifting, and participle clauses. B2 is the standard target for university entrance exams (IELTS 5.5–6.5, TOEFL 87–109) and most skilled-migration thresholds — knowing whether you're there shapes your study plan.
Difficulty: Medium
The Medium difficulty tag marks questions and challenges in the middle of the difficulty range — typically suitable for A2 to B1 learners. Expect a single rule with realistic distractors, longer sentences, and contexts where you have to think before answering rather than reading off the obvious choice.
Filter by Medium when you're past the absolute basics and ready to consolidate. It's the level where most lasting progress happens — easy enough that you can finish without exhausting concentration, hard enough that getting it right means you've actually understood.