－How was your day off yesterday?－Perfect! It was birthday of my grandpa’s . We had a big

问题补充：

－How was your day off yesterday?

－Perfect! It was birthday of my grandpa’s . We had a big family celebration.

A. seventy B. seventieth C. the seventieth

答案：

解析：考查序数词。我爷爷七十岁的生日，“七十”要用序数词形式，在表述时前面加”the”表示“第七十”的意思。