33. Why does Hawking communicate with others through a computer?

A. He is too weak to speak.

B. He is a computer addict.

C. An operation to help his breathing made him unable to pronounce.

D. His illness makes him unable to speak.

34. The leading theoretical physicists are searching for a "theory of everything" because ____________.

A. the existing theories are out of date

B. the theories are not enough

C. some of the theories are wrong

D. the existing theories are somewhat contradictory to each other

35. Hawking and his colleagues are working hard to try to find ____________.

A. a new theory to replace the Big Bang theory

B. a new theory to replace Einstein´s general theory of relativity

C. a theory that can incorporate the existing theories

D. an all-powerful theory that can explain everything in the world