俄罗斯第二大城市和重要港口是（   ）

根据材料内容，选择正确答案。

    Hi, boys and girls! My name is Gina. I'm an assistant at Mr. Miller's Store. Now let me say something about the store. On the first floor (层), we sell clothes for girls. The skirts in white, red, black and yellow are only $35. We have socks in all colors. They're only $8 for two pairs. How much are our sweaters? Only $25!

    If you are a boy, you can go to the second floor. Look at those baseball hats. Do you like them? They are only $6. Are you very fat? We have some big jackets for you. They are $40. We have some shorts, too. They are only $18.

    What do you need? Come to Mr. Miller's Store now!

猜一猜。

千条线，万条线，落到河里看不见。谜底____