{{i}} quEstions 4 to 7 ArE BAsED on thE Following ConvErsAtion.At thE EnD oF thE ConvErsAtion, you will BE givEn 20 sEConDs to AnswEr thE quEstions. now listEn to thE ConvErsAtion.{{/i}}

EACh oF thosE mAChinEs CAn only pErForm ______.A．mAny opErAtions
B．two opErAtions
C．A singlE opErAtion
D．nonE oF opErAtions