yǐn xiàn 
		fuse (for an explosive device)
electrical lead
intermediary
catalyst
(dialect) sewing needle
		 
		
		
		
		
			 
		
				
		
			chuān zhēn yǐn xiàn 
		lit. to thread a needle (idiom); fig. to act as a go-between
		 
		
		
														
		
		
			 
		
				
		
			yǐn xiàn chuān zhēn 
		a pull-through to thread a needle
fig. to act as go-between