phrases with AT

I've finished my writing......(at least / at once / at long last)

There are ................ 300 million people in the USA (at its best / at least / at first)

Many wild animals are ............. because of the fires in the North of the country. (at its best / at least /at risk)

If ............. you don't succeed, try, try again. (at first / at present / at long last)

I can't be in two places............... It's impossible (at risk / at its best / at once)

..................... there are only around 70,000 orangutans left in the wild. (at present / at least / at its best)

The gorgeous landscape shows the Iguazú Falls................. (at its best / at present / at risk)

"Leave my property ........", he shouted ( at first / at long last/ at once)