Constructs an empty table using `a` and default hash function and key equality predicate, and inserts the elements from `il` into it.
Constructs an empty table using `a` and default hash function and key equality predicate, and inserts the elements from `il` into it.构造一个使用分配器`a`、默认哈希函数和键相等谓词的空容器，并将`il`中的元素插入其中。
admin
Constructs an empty table using `a` and default hash function and key equality predicate, and inserts the elements from `il` into it.构造一个使用分配器`a`、默认哈希函数和键相等谓词的空容器，并将`il`中的元素插入其中。