At-Phrases and For-Phrases

Fixed expressions with 'at' and 'for': at least, at once, at first, for free, for good, for sale. Essential B1–B2 phrases for expressing quantity, time, and permanence.

At-Phrases and For-Phrases in English

'At' and 'for' both form a rich set of fixed adverbial phrases. These two prepositions are grouped together in this subtopic because several of their phrases involve near-confusables ('at first' vs 'in first', 'for free' vs 'in free'). Frequency data from the British National Corpus places 'at least', 'at once', 'for free', and 'for good' among the most common fixed prepositional adverbials in everyday English.

Core At-Phrases

at least — There were at least fifty people at the concert.
at once — The doctor said she needs to rest at once. (= immediately)
at first — At first, I didn't like the city, but now I love it.

Core For-Phrases

for free — The museum is open for free on Sundays.
for good — She's left the company for good. (= permanently, forever)
for sale — Is this house for sale? (= available to buy)

'At First' vs 'In the End'

These two phrases often appear together to describe a change over time: 'At first I was nervous, but in the end everything went well.' Note: 'in first' and 'at the end' (without 'of') are both incorrect in this usage.

Common Mistakes

✗ You should book in least two weeks ahead. → ✓ You should book at least two weeks ahead.
✗ In first, I didn't like the city. → ✓ At first, I didn't like the city.
✗ She's left for good. → ✓ She's left for good. (This one is correct — 'for good' uses 'for'.)