Look and write.(选出下列单词中所缺的字母，写在横线上)

    1. f   sh                      2. gra    dma                3. hamb    rger

      (i, f )                              (a, n)                             (h, u)

  4.     oman                     5. br  ther                        6.    ce

      (w, g)                            (e, o)                             (i, d)

二站闪蒸酸浴贮槽的材质是（）。

A、A3

B、树脂

C、PVC

D、钢衬胶