A．To learn how to prevent a bone disease.
B．To understand differences between bone tissue and other tissue.
C．To find out how specialized bone cells have evolved.
D．To create artificial bone tissue.

A．She prefers the job where he could travel a lot.
B．She prefers the job where she could make good money.
C．She prefers the job where she could meet international business people.
D．She prefers the job that would give her lots of chances of promotion.