⑴ 他大约是一个70岁的老爷爷用英语怎么说
He is an old man who is almost eighty years old.
eight-year-old,通常用在名词前,作定语
eight years old,通常用在be动词后,作表语
His brother is eight years old.
The eight-year-old boy is his brother.
望采纳，谢谢！
⑵ 他是一个八十岁的男人英文同意句
他是一个八十岁的男人
那么经过翻译之后
得到的英文同义句就是
He is a eighty old man.
或者说The old man is eighty years old.也可以
⑶ “一个80岁的老人”用英语怎么说
an eighty-year-old man
这是最规范的写法，也是最正确的
⑷ 我爸80岁用英文翻译怎么说
我爸80岁
My dad is 80 years old.
请采纳