It's three miles后加away还是不加?

It's three miles后加away还是不加? Piccadilly Circus?It’s 4 miles away. it's only three miles ___my house it's five miles away from here.it's five miles away 都对吗 . It was a three-hour journey 中的hour为什么不加S,不是复数要加S的吗? often后加ing还是加s还是动词原形? about后加hundreds of还是three hundred(具体数字) what's the price of 后加复数 回答用it's 还是they are three hundred pounds 为什么加S four thousand people 为什么不加S It`s an eraser.为什么加an不加a it is 后加形容词还是副词? any question后为什么不加s