off balance - unaware; off guard

　　on the go - working or doing something all the time

　　on pins and needles - nervous; anxious; full of anticipation

　　on purpose - deliberately; intentionally

　　on the blink - not working properly;broken

　　pick up the tab - pay the bill or the cost of something

　　piece of cake - easy

　　play by ear - act spontaneously; without planning

　　pill it off - accomplish

　　pull one’s leg - make fun of somenoe in a playgul way; make somenoe believe something that is not ture

　　quite a few - many  （编辑：雨巷）