新银盐光度法测定水中砷，可用乙酸铅棉去除硫化物干扰。
参考答案：对
— My father _____ Shanghai with my grandparents.
— Really? _____ will they come back? [ ]
A. has been to; How soon
B. has gone to; How soon
C. has been to; How long
D. has gone to; How long
栈通常采用的两种存储结构是
A．线性存储结构和链表存储结构
B．散列方式和索引方式
C．链表存储结构和数组
D．线性存储结构和非线性存储结构
