01 / 07
What are non-defining relative clauses?
Non-defining relative clauses add removable information about a person or thing that is already clearly identified. In "My manager, who works in Berlin, approved the budget," the listener already knows which manager is meant; the location simply adds background. Remove who works in Berlin and "My manager approved the budget" remains complete, with the same person in view. That is the most reliable meaning test. The commas tell the reader that the inserted words do not select one person or thing from a wider set. In speech, this bracket is often audible as a brief pause before the clause and a low fall inside it. The construction makes reports compact because it combines a main message with useful context without turning that context into a condition for identifying the referent.
02 / 07
When do you use a comma before *which*?
Use a comma before which when the clause adds non-defining information, and add a second comma if the main clause continues afterwards. The compact pattern is identified referent, who/which/whose + extra detail, main clause. In "The Q3 report, which finance published on Monday, shows strong demand," the two commas bracket the publication detail. If the extra comment comes at the end, the opening comma is enough: "The client moved the deadline, which delayed the project." The comma therefore follows from meaning rather than appearing mechanically before every instance of which. In a defining relative clause, which can occur without a comma when the clause identifies the intended thing. First ask whether the referent is already clear and the detail can be removed; then apply the matching comma pattern.
03 / 07
When do you use *who*, *whose*, and *which*?
Use who for people, whose for possession, and which for things or a comment on the whole previous sentence. "My manager, who works in Berlin, approved the budget" adds information about a person. Whose can add a compact possession link: "Maya, whose team led the review, presented the result." Keep that form recap short; at B2, the more important decision is whether the information identifies the referent or merely supplements it. For things, use which: "Our new CRM system, which we launched in March, already saves us hours." In "The client moved the deadline, which delayed the project," which does not refer to one noun alone; it comments on the complete preceding event. Check the reference each time: person, possession, thing, or whole situation.
04 / 07
What is the difference between defining and non-defining relative clauses?
Defining and non-defining relative clauses differ in whether the clause selects the intended group or merely adds a fact about a group that is already fixed. Compare "The suppliers who were late got a warning" with "The suppliers, who were late, got a warning." Without commas, only the late suppliers received a warning; other suppliers may have been on time. With commas, all the identified suppliers were late, and their lateness is additional information. The word order is nearly identical, but the punctuation changes the scope of the claim. This is therefore not decorative style, nor is it a prohibition based on sentence length. The key issue is which people or things the listener should identify. Read the referent and relative clause separately: if the selection stays the same, the comma version fits; if the clause creates the intended subgroup, use the defining version without commas.
05 / 07
Why do *that* and *what* fail after the comma?
After the comma in a non-defining relative clause, use who, whose, or which, not that or what transferred from German was. German speakers can use forms related to der, die, or das across several relative patterns, so that can feel overly flexible: "My manager, that works in Berlin, approved the budget." The natural correction is "My manager, who works in Berlin, approved the budget." For a thing, change "Our new CRM system, that we launched in March" to "Our new CRM system, which we launched in March." A second transfer error follows a whole sentence: "The client moved the deadline, what delayed the project." Use which because it picks up the preceding event. The practical decision is simple: after the comma boundary, choose the pronoun by its reference rather than treating that or what as a universal substitute.
06 / 07
How do you use non-defining relative clauses in reports?
In reports and documentation, use non-defining relative clauses to add concise background about known people, locations, or documents. "Our Munich office, which opened in 2019, now serves Austria" connects its current responsibility with its opening year. "The Q3 report, which finance published on Monday, shows strong demand" gives the publication detail and result without producing two choppy sentences. For a person, you might write "Lena, who managed the rollout, documented every issue." A whole-sentence comment is especially useful for consequences: "The client moved the deadline, which delayed the project." Keep the main message easy to recognise, however. If several long additions overload the sentence, split them into two sentences. There is no rule requiring every background fact to become a relative clause; use the construction when the detail is genuinely supplementary and makes the report easier to read.
07 / 07
How can you check a non-defining relative clause?
Check a non-defining relative clause with three questions: is the referent already identified, does it remain the same after removing the detail, and does the chosen pronoun match its reference? Start with the core sentence. Remove the middle from "The Q3 report, which finance published on Monday, shows strong demand" and you get "The Q3 report shows strong demand." The report remains identified, so the publication detail can be supplementary. Then add both commas and choose among who, whose, and which. Read the finished sentence aloud; a brief pause before the addition and a low fall help make the written bracket audible. For a sentence comment, also check that which genuinely summarises the whole preceding event. This meaning test is more reliable than searching mechanically for individual words, and it prevents you from placing commas by instinct alone.