Table 3. Uni-gram, bi-gram and tri-gram probabilities for a question.

Unigram	Unigram probability	Bi-gram	Bigram probability	Tri-gram	Tri-gram probability
what	0.069	what different	0.034	what different type	0.294
different	0.007	different type	0.157	different type operator	0.117
type	0.008	type operator	0.023	type operator use	0.333
operator	0.006	operator use	0.067	operator use Java	0.166
use	0.008	use Java	0.024
Java	0.042