The correct answers are Swimming keeps me healthy and I love hiking in the mountains.
"Swimming" is a gerund acting as the subject (noun) of the sentence. "Hiking" is a gerund acting as the object (noun) of "love." In contrast, "swimming" in "swimming pool" is a participle describing the noun "pool," and "dancing" is part of the continuous verb phrase "is dancing."
Gerund
If you've ever said I enjoy to read or good at to swim and wondered why it sounded wrong, you've met the gerund. English is fussy about which structures take -ing and which take to + verb, and getting this wrong is one of the most common giveaways that someone learned grammar from a list rather than from real usage.
A gerund is the -ing form of a verb acting as a noun — reading, swimming, being late. After many common verbs (enjoy, avoid, finish) and after every preposition, English demands the gerund, never the infinitive.
Participle
If you've ever written I should have went and been corrected to should have gone — you've hit the past participle's main rule. The participle isn't an exotic form; it's the workhorse that builds perfect tenses, passive voice, and dozens of common adjectives. Get the irregular ones automatic and your tenses fall into place.
A participle is a verb form acting as an adjective or adverb. The present participle is the -ing form (running, sitting); the past participle is -ed (regular: walked) or irregular (broken, gone, written). Participles build perfect tenses, progressive tenses, and the passive.
B1 | Intermediate
If you can hold a conversation about your weekend, explain why you're late, and follow a short news story without panicking — but still feel lost in fast or technical English — you're probably operating at B1. Knowing this matters: study material at the wrong level either bores you or burns you out, and B1 is the typical target for travel, casual work, and most everyday social English.
B1 is the intermediate level in the CEFR framework, where you handle everyday English independently and start combining ideas with complex sentences, passive voice, and modal verbs.
Difficulty: Medium
If easy questions feel too obvious but hard questions leave you guessing, you're probably ready for Medium — the level where most real learning happens. It pushes just enough to expose the rules you don't quite have yet, without burying you in edge cases. This is where steady fluency is built, one well-aimed challenge at a time.
The Medium difficulty tag marks middle-range challenges — typically A2 to B1. One rule per question, realistic distractors, and contexts that require active thought rather than instant recognition.