看图，对划线部分提问。

1. Yao Ming is writing a letter.

    _________is Yao Ming _________?

2. Yao Ming's stamp is one yuan.

    _______ _______ is Yao Ming's stamp?

3. Yao Ming needs eight postcards.

    ________ ________ postcards does Yao Ming need?

4. Yao Ming is sending the letter to America.

    _________ is Yao Ming sending the letter?

由拍卖人事先公布每批商品的具体情况和拍卖条件，然后由竞买者在规定时间内将密封标书递交拍卖人，由拍卖人选择条件最合适者表示接受而成交的方式叫（）

A.增价拍卖

B.减价拍卖

C.密封递价拍卖

D.正式拍卖