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单价合同大多用于工期长、技术复杂、实施过程中发生各种不可预见因素较多的大型复杂工程的施工，以及业主为了缩短项目建设周期，初步设计完成后就进行施工招标的工程。（）

植物常用的分类单位是 [ ]

A．界、门、纲、目、科、种    

B．门、纲、目、科、属、种  

C．种、属、科、目、纲、门    

D．门、纲、科、目、种、属

Windows XP内置的Windows防火墙可以限制从其他计算机发送到本地计算机上的信息，从而提高计算机的安全性。Windows防火墙有三种设置：“开”、“开并且无例外”和“（）”。

根据所给词的适当形式填空。

1. Oven______ (become) a famous professional soccer player when he was 20 years old.

2. Did you remember the great ______? He often takes part in ______ competition (skate).

3. September is the ______ (nine) month of a year. I was born in September and I had ______a

    (nine, year) memory (记忆) of my life.

4. The teacher spent a whole day ______ (look) for the lost student yesterday.

5. ______ (win) the first prize in the Olympic Games is an excellent honor.

6. The old man is too weak (弱的) ______ (carry) the box of apples. Let's ______ (help) him.

7. The policeman stopped the driver______ (drive) the car because its speed (速度) is too fast.

8. Last year, he ______ (enter) the university and now she ______ (major) in English Education.

9. Miss Zhao is a ______ (love) teacher, she is friendly to her students.

10. Have you watched the movie ______ (call) the Hero (英雄)?

系统误差具有()。

A．不确定性

B．不可预知性

C．累加性

D．严重性