A.professor
B.storm
C.ordinary
D.short

A．To tell campus personnel of the new library services.
B．To announce the new movies on campus this summer.
C．To notify university people of important schedule changes.
D．To remind students to validate (使生效) their identification cards.

A．viruses are known to cause cancer in animals
B．at present, human cancer is not believed to be contagious (传染的)
C．there are many known causes for the transformation of a normal cell to a cancer cell
D．results of experiments on plants and animals do not vary greatly from species tn species