问题
Walk along the street, and you can see a bookstore _______the street.
A:a 18-year-old
B:a 18-years-old
C:an 18-years-old
D:an 18-year-old;
B:a 18-years-old
C:an 18-years-old
D:an 18-year-old;
正确答案是：
