两者均可表示“快”,在口语中,一般多用quick(尤其在需要用比较级或最高级时),并且总是放在动词之后；若放在动词之前,一般用quickly.
如：
Come quick(ly).There’s been an accident.快来,出事故了.
You get there quicker by bus.你坐汽车去那儿会快一些.
He quickly changed his clothes.他迅速地换了衣服.
The evening passed quickly.晚上很快过去了.
He ran as quickly as he could.他使劲地跑.