A．Language was the first invention of mankind.
B．There was no greater invention than language.
C．Most of man’s inventions depended on language.
D．There were so many languages in the world.

A．No, it’s open only to teachers and postgraduates.
B．Yes, he can study there if he is writing a research paper.
C．Yes, because he is a senior student.
D．Yes, but he needs the approval of his professor.