the book store is open ,l----go ang buy soom books.
问题描述：
the book store is open ,l----go ang buy soom books.
a could
b couldn't
c did can
d should
选什么 为什么
答
should 既然书店是开着的,可以排除 b 和 c ,c 语法都不通.
a 不对是因为 could 是过去式,但前面有is ,所以不可能,