Learned by Reading
In Wikipedia:
Several allotropes of boron exist; amorphous boron is a brown powder, though crystalline boron is black, extremely hard (9.3 on Mohs’ scale), and a poor conductor at room temperature.
(Parse)
(S1 (S (S (NP (NP (JJ Several) (NNS allotropes))
(PP (IN of)
(NP (NN boron))))
(VP (VBP exist)))
(: ;)
(S (NP (JJ amorphous) (NN boron))
(VP (AUX is)
(NP (DT a) (JJ brown) (NNP powder)) (, ,)
(SBAR (IN though)
(S (NP (JJ crystalline) (NN boron))
(VP (AUX is)
(NP (NP (JJ black)) (, ,)
(NP (RB extremely) (JJ hard) (PRN (-LRB- -LRB-)
(NP (NP (CD 9.3))
(PP (IN on)
(NP (NP (NNP Mohs) (POS ')) (NN scale))))
(-RRB- -RRB-)))
(, ,) (CC and)
(NP (NP (DT a) (JJ poor) (NN conductor))
(PP (IN at)
(NP (NN room) (NN temperature))))
(. .)))
In Wikipedia:
Crystalline boron has four major polymorphs:,, and T.
(Parse)
(S1 (S (NP (JJ Crystalline) (NN boron))
(VP (AUX has)
(NP (NP (CD four) (JJ major) (NNS polymorphs)) (: :)
(NP (NP (CD )) (, ,)
(NP (NP (NNP ) (NNP )) (, ,)
(NP (NNP ) (NNP )) (CC and)
(NP (NNP T)))
(. .)))
In Wikipedia:
Crystalline boron is a very hard (Vickers hardness comparable to that of cubic boron nitride), black, diamagnetic material with a melting point of 2080 C.
(Parse)
(S1 (S (NP (JJ Crystalline) (NN boron))
(VP (AUX is)
(NP (NP (DT a)
(ADJP (ADJP (RB very) (JJ hard)) (PRN (-LRB- -LRB-)
(NP (NNP Vickers) (NN hardness))
(ADJP (JJ comparable)
(PP (TO to)
(NP (NP (DT that))
(PP (IN of)
(NP (JJ cubic) (NN boron) (NN nitride)))
(-RRB- -RRB-)))
(, ,) (JJ black) (, ,) (JJ diamagnetic) (NN material))
(PP (IN with)
(NP (NP (DT a) (NN melting) (NN point))
(PP (IN of)
(NP (CD 2080) (NNP ) (NNP ) (NNP C))))
(. .)))
In Wikipedia:
The average cost of crystalline boron is $ 5 / g.
(Parse)
(S1 (S (NP (NP (DT The) (JJ average) (NN cost))
(PP (IN of)
(NP (JJ crystalline) (NN boron))))
(VP (AUX is)
(NP (ADJP (QP ($ $) (CD 5) (CD /)))
(NNP g)))
(. .)))
In Wikipedia:
Crystalline boron is a very hard, black material with a high melting point and exists in many polymorphs: Two rhombohedral forms, – boron and – boron containing 12 and 106.7 atoms in the rhombohedral unit cell respectively, and 50 – atom tetragonal boron are the most common.
(Parse)
(S1 (S (S (NP (JJ Crystalline) (NN boron))
(VP (VP (AUX is)
(NP (NP (DT a)
(ADJP (RB very) (JJ hard)) (, ,) (JJ black) (NN material))
(PP (IN with)
(NP (DT a) (JJ high) (NN melting) (NN point)))))
(CC and)
(VP (VBZ exists)
(PP (IN in)
(NP (JJ many) (NNS polymorphs)))
(: :)
(S (NP (NP (CD Two) (JJ rhombohedral) (NNS forms)) (, ,)
(NP (NP (NNS )) (: -)
(NP (NN boron) (CC and) (NN ) (NNS )) (: -)
(NP (NP (NN boron))
(VP (VBG containing)
(NP (NP (NP (QP (CD 12) (CC and) (CD 106.7)) (NNS atoms))
(PP (IN in)
(NP (NP (DT the) (JJ rhombohedral) (NN unit) (NN cell)) (ADVP (RB respectively)))))
(, ,) (CC and)
(NP (CD 50)))))
(: -)
(NP (JJ atom) (JJ tetragonal) (NN boron))))
(VP (AUX are)
(NP (DT the)
(ADJP (RBS most) (JJ common)))))
(. .)))
In Wikipedia:
Crystalline boron is chemically inert and resistant to attack by boiling HF or HCl.
(Parse)
(S1 (S (NP (JJ Crystalline) (NN boron))
(VP (AUX is)
(ADJP (RB chemically) (JJ inert) (CC and) (JJ resistant)
(S (VP (TO to)
(VP (VB attack)
(PP (IN by)
(S (VP (VBG boiling)
(NP (NNP HF) (CC or) (NNP HCl.))))))))))))
In Wikipedia:
Elemental boron can exist in several allotropes, the most common of which are crystalline boron and brown amorphous boron.
(Parse)
(S1 (S (NP (JJ Elemental) (NN boron))
(VP (MD can)
(VP (VB exist)
(PP (IN in)
(NP (NP (JJ several) (NNS allotropes)) (, ,)
(SBAR (WHNP (NP (DT the)
(ADJP (RBS most) (JJ common)))
(WHPP (IN of) (WHNP (WDT which))))
(S (VP (AUX are)
(NP (NP (JJ crystalline) (NN boron)) (CC and)
(NP (JJ brown) (JJ amorphous) (NN boron))))
(. .)))
In Wikipedia:
Crystalline boron is a very hard, black material with a high melting point.
(Parse)
(S1 (S (NP (JJ Crystalline) (NN boron))
(VP (AUX is)
(NP (NP (DT a)
(ADJP (RB very) (JJ hard)) (, ,) (JJ black) (NN material))
(PP (IN with)
(NP (DT a) (JJ high) (NN melting) (NN point)))))
(. .)))