1. hurdle   noun   

原句: His research led him to conclude that the language barrier is but one hurdle between cultures.

意思: a problem or difficulty that must be solved or dealt with before you can achieve sth

字源: Old English hyrdel ‘temporary fence’, of Germanic origin; related to Dutch horde and German Hürde. 

例句: We'll cross that hurdle when we come to it.

1. taboo   noun   

原句: A practice that's a social taboo back home.

意思: a cultural or religious custom that does not allow people to do, use or talk about a particular thing as people find it offensive or embarrassing

字源: late 18th cent.: from Tongan tabu ‘set apart, forbidden’; introduced into English by Captain Cook. 

例句: Death is one of the great taboos in our culture.