HOW/ UNGRATEFUL/ YOU/ NOT GREET/ FORMER TEACHER/ MEET/ HIM//A.HOW...
51. How/ ungrateful/ you/ not greet/ former teacher/ meet/ him//
a.How ungrateful of you not to greet your former teacher when you met him.
b. How ungrateful you are not to greet your former teacher when you met him.
c. How ungrateful to you not to greet your former teacher when you met him.
d. How ungrateful of you not to greet your former teacher when meet him.