Two sentences can become one, and one can become two. Neither move changes a single word, and both change the shape of the information enough to count as a genuine rewrite. This is the technique that makes a paraphrase stop looking like the original once the words themselves have been moved as far as they will go.
Joining is the more useful direction, because it forces you to state a relationship. Two sentences side by side leave the reader to guess how they connect; “Although X, Y” says it out loud. That is not only paraphrase, it is better writing — and it is assessed under Coherence and Cohesion, where making a relationship explicit is precisely what is being looked for.
Splitting is the emergency move. A long prompt sentence with three clauses can be broken at its natural joint, which is often the fastest route to something that reads nothing like the original. Shorter sentences are not simpler writing: knowing where the joint is, is the skill.
“X. Y.” → “Although X, Y.” The second sentence loses its full stop and gains a stated relationship.
“The scheme cost £2bn. It was abandoned.” → “The scheme, which cost £2bn, was abandoned.” The commas decide whether the clause identifies or merely adds.
“Because it lacked funding, the project stalled” → “Lacking funding, the project stalled.” The participle must belong to the subject that follows it.
A comma cannot join two complete sentences, and “however” cannot rescue it. It is the most common punctuation error in Task 2.
