Plurals and prepositions: the errors that repeat in every essay
8 min
In Mandarin, 三本书 uses the same noun 书 as 一本书 — quantity is carried entirely by the number and measure word, and the noun itself never changes. English instead requires the noun to change ("three books") independent of whether a number is even present: "many students", "few resources", "most countries" all need the plural noun even though no digit appears. Under time pressure, Chinese speakers reliably drop the -s specifically in two places: after quantity words other than a literal number (many, several, various, a range of), and on nouns separated from their quantity word by other words ("the three most important factor" — the adjective "important" sits between "three" and the noun, making it easy to forget the noun needs marking too). The fix during proofreading is mechanical: find every plural quantity word and trace forward to its noun, no matter how many words sit between them.
Prepositions cause more errors than almost any other word class because Mandarin coverbs (在, 于, 关于, 依赖) do not map one-to-one onto English prepositions — the mapping has to be memorized case by case, not translated. Four patterns cover a large share of exam errors. Time: use "in" for months/years/decades ("in July", "in 2020"), "on" for days and dates ("on Monday", "on July 3rd"), "at" for clock times and a few fixed points ("at 9 a.m.", "at night"). Place follows the same logic: "in" for enclosed areas or large regions ("in Taipei", "in the room"), "on" for surfaces ("on the table", "on page 12"), "at" for specific points ("at the entrance", "at the corner"). Two verbs are worth memorizing as exceptions because they take no preposition at all where a direct Mandarin translation would suggest one: "discuss" (not "discuss about") and "attend" (not "attend to" when it means "go to" an event). And "depend on" is the fixed pairing — never "depend to" or "depend for".
Worked example
Weak: "The success of a business depend on many factor, including the skill of its employee and the condition of the market. Managers should discuss about these issue at monthly meeting." Strong: "The success of a business depends on many factors, including the skills of its employees and the condition of the market. Managers should discuss these issues at monthly meetings."
Three separate plural nouns lose their -s ("factors", "skills", "issues", "meetings") because each sits after a quantity word or plural context but the writer's attention was on meaning, not marking. "Depend on" is correct in both versions — the error to watch for is dropping "on" entirely, which is common when translating directly from 依赖. "Discuss about" is the single highest-frequency preposition error in this passage: "discuss" already means "talk about", so adding "about" is redundant in a way English does not permit. Note "at monthly meetings" is also plural — a recurring event referred to generally takes the plural, matching the same quantity-word logic as nouns elsewhere.