用所给单词的适当形式填空

1. Is this______ (you) ruler?

2. Excuse______(I),are______(your) Li Ming?

3. What's______(he)name?

4. ______(she)last name is Smith.

5. I have a set of______(key).

6. ______(be) your ruler yellow?

7. Please______(spell) your name.

8. It_______(not be)my ID card.

9. It is _______(I) pencil case.

下列那种措施是防止近交衰退最有效的措施（）。

A、异质选配

B、选择+淘汰

C、环境控制

D、后裔测定