Breakdown of Ellos practicaron el bloqueo, el cual es muy útil.
ser
to be
ellos
they
practicar
to practice
muy
very
Questions & Answers about Ellos practicaron el bloqueo, el cual es muy útil.
Why use el cual instead of que here?
Both are grammatically correct. Que is the most common relative pronoun, but in non-defining relative clauses—the ones set off by commas that just add extra information—you can use el cual instead. It sounds a bit more formal and is very common in writing.
Could I use lo cual instead of el cual here?
No, because the pronoun refers back to a specific noun: el bloqueo, which is masculine and singular. You must use el cual to match its gender and number. You would only use the neuter lo cual if 'which' referred to the entire previous situation or action (the fact that they practiced), rather than just the block itself.
What happens if I remove the comma before el cual?
You would have to change el cual to que. When acting as the subject of the clause, el cual is only allowed in non-defining clauses (clauses with commas). If you drop the comma to make the information essential to identifying the block, you are forced to use que: Ellos practicaron el bloqueo que es muy útil.
Just as a refresher, why does útil have a written accent?