Parallel structure

Read the first item, then try each later item in the same slot. If the program teaches employees monitoring sounds wrong on its own, the item is not parallel. The error is almost always in the last element, because that is where writers lose the thread — so check the last one first.

Whatever follows the first half must match what follows the second: both…and, either…or, neither…nor, not only…but also, whether…or. Cover the first half and read the second alone — if it needs a word the first half supplied, the pair is unbalanced.

A series is either all gerunds or all infinitives. Which one you need is decided by the word in front of the series, not by preference: enjoys reading and hopes to read are both fixed, and the whole list follows whichever the governing word demands.

Both versions above are correct. What is not allowed is repeating to for some items and dropping it for others. The same all-or-nothing rule governs a repeated article, auxiliary or preposition across a list.

Switching voice mid-series changes the subject halfway through and breaks the line the reader is following. Pick the voice that suits the whole sentence and keep it. The giveaway is a new subject appearing inside what should be a list of verbs.

Adjectives pair with adjectives, nouns with nouns, clauses with clauses. Swapping a clause into a list of adjectives is the most common version, and it usually means an adjective exists that the writer did not reach for: reliability for because she was reliable, communicative for who communicates well.

When two or more clauses hang from the same verb, each needs its own that, or the reader briefly parses the second clause as a new main sentence. The same applies to who, which and whether in a series of clauses.

The wrong version promises a second verb and never supplies one. Place each half of the pair immediately before the elements being joined: if you are joining two nouns, both halves sit in front of nouns; if you are joining two verbs, both sit in front of verbs.

The faulty version compares a climate to a country. Supply that of for a singular noun and those of for a plural one, or repeat the noun. The same logic governs like and unlike: unlike the earlier study, this one surveyed 400 cases, not unlike the earlier study, the sample was larger.

Prefer pairs with to, never with than: prefer X to Y or would rather X than Y. Whatever sits on both sides of rather than, as well as and instead of must also match in form, since those phrases join two elements exactly as and does.

Two halves can share a word only if both halves actually take it. Interested needs in, so it cannot borrow the to that belongs to committed. The same trap appears with verb forms: has never and will never accept is faulty because has never accept is not English — write has never accepted and will never accept.

Everything after a colon or after the following belongs to one list and takes one form. This matters most in the writing tasks, where a list that starts with noun phrases and drifts into full sentences reads as carelessness even when every individual item is grammatical.