{{i}}quEstions 19-22 ArE BAsED on thE Following DiAloguE:{{/i}}

whAt DiD thE proFEssor wAnt to tAlk toAnn ABoutA、vACAtion trip to yEllowstonE pArk.
B．A、lECturE By A visiting proFEssor.
C．hEr Biology thEsis.
D．A、rEsEArCh projECt.