—Hey, you look concerned. What’s on your mind
—The final exam.（）

A．told about their houses
B．entertained
C．silly
D．very worried about their houses

A．200,000 acres in about 15 hours
B．about 1,333 acres in about 1 hour
C．about 3,000 acres in 2 hours
D．70 miles in more than 15 hours