(1) Loom large = If something looms large it becomes very important and often causes worry.
- The thought of a third world war looms large in the minds of the humanity.
- Fear of failure loomed large in his mind.
(2) won’t budge an inch = will not move, change or shift in any way at all.
- Once my brother gets his mind made up, he won’t budge an inch. So don’t bother trying to reason with him.
- I can’t believe how tight this bolt is on here, it won’t budge an inch.
. (3) An unknown quantity = A person or a thing whose abilities, powers or effects are not yet known.
- We are still revising our new product, so its potential success is an unknown quantity.
- He is an unknown quantity for his rivals.