所有分子标记技术的用途基本一致。

句型转换。

1. He goes home by bus every day.(同义句)

    He _____ _____  _____  home every day.

2. Andy can put the football behind the door. (划线提问) 

    _____ _____  Andy put the football?

3. They have five lessons every day. (划线提问)

    _____ _____ _____ _____  they have every day?

4. Ann does her homework in the evening. (一般疑问句)

    _____ Ann _____ _____ homework in the evening?

5. Nick often cooks dinner at the weekend. (划线提问)

    _____ _____  Nick often _____ at the weekend?

6. The boy under the tree is my brother. (划线提问)

    _____ _____ is_____ brother?

7. The teddy bear is the twins'. (划线提问)

    _____ _____ the teddy bear?

测定DNA溶液浓度时，通常选择的波长是（）。

A.220nm

B.260nm

C.300nm

D.320nm

E.360nm

下列会计凭证中，属于外来原始凭证的是( )。

A．收料单

B．购货时取得的发票

C．销货发票

D．成本计算单

根据《中华人民共和国民用航空法》，民用航空器可以具有双重国籍｡

直接接触食品用复合塑料购物袋应符合（）。

A.GB 9687

B.GB 9688

C.GB 9681

D.GB 9683