Grammar of Time: By, Until, During, While
Distinguish similar time words.
Examples
- by Friday
- until Friday
Key rules
- By = not later than
- Until = up to a time and continues
- During + noun, while + clause
- For = length, since = starting point
Common mistakes
- I will work by Friday (all week) → I will work until Friday
- I slept while the film → I slept during the film
💡 Tip: By is a deadline, until is duration.