How could such a thing happen?
1	How	how	ADV	B	_	6	advmod	_	_
2	could	can	AUX	VM	Mood=Ind|Person=3|Tense=Past|VerbForm=Fin	6	aux	_	_
3	such	such	DET	DD	PronType=Dem	5	det:predet	_	_
4	a	a	DET	RI	Definite=Ind|Number=Sing|PronType=Art	5	det	_	_
5	thing	thing	NOUN	S	Number=Sing	6	nsubj	_	_
6	happen	happen	VERB	V	VerbForm=Inf	0	root	_	SpaceAfter=No
7	?	?	PUNCT	FS	_	6	punct	_	_
