Questions 6 to 10 are based on the following news.

A．unable to influence the behavior of his successors
B．cheated by his own successors
C．determined to take revenge on his enemies
D．more generous to his enemies than his successors

A．Mathematicians would like to spare no effort to make their proofs elegant.
B．Mathematicians love to arrange their formulas and equations so that they take a beautiful form.
C．Mathematicians often arrange their formulas and equations in symmetry.
D．Mathematicians like to arrange their formulas in verses.