Research into the causes of cancer reveals that we are still unsure of its precise causes.

A．the basis for decision making and problem solving
B．an ability to store experiences for future use
C．an intelligence typically possessed by human beings
D．the data mainly consisting of words and combinations of words

A．What would life be like without memory
B．Memory is of vital importance to life.
C．How is a person's memory different from an animal's or a computer's
D．What is contained in memory