—David how old is your father this year?—. And we just had a special party for his birth

问题补充：

—David, how old is your father this year?

—. And we just had a special party for his birthday last weekend.

A. Fortieth; forty

B. Forty; forty

C. Forty; fortieth

D. Fortieth; fortieth

答案：

A. Fortieth; forty

B. Forty; forty

(答案→)C. Forty; fortieth

D. Fortieth; fortieth

解析：数词的考查。年龄的表达应该是基数词，但当表示某人多大生日的时候应该是序数词，故C是正确的。