VOCAB!

stumble

v stumble [ˈstambl]

1 to strike the foot against something and lose one's balance, or nearly fall He stumbled over the edge of the carpet. 绊倒

2 to walk unsteadily He stumbled along the track in the dark. 蹒跚

3 to make mistakes, or hesitate in speaking, reading aloud etc He stumbles over his words when speaking in public. 结结巴巴地说（读）

n stumbling-block

a difficulty that prevents progress. 绊脚石

stumble across/on

to find by chance I stumbled across this book today in a shop. 偶尔发现


USEFUL DICTIONARY:http://www.freedictionary.com/