关于光学器材或设备，下列说法错误的是（ ） A．照相机、幻灯机的镜头都相当于凸透

某原电池总反应为2Fe³⁺+Fe＝3Fe²⁺，不能实现该反应的原电池是 [ ]

A．正极为Cu，负极为Fe，电解质溶液为FeCl₃

B．正极为C，负极为Fe，电解质溶液为Fe(NO₃)₃

C．正极为Fe，负极为Zn，电解质溶液为Fe₂(SO₄)₃

D．正极为Ag，负极为Fe，电解质溶液为Fe₂(SO₄)₃

负反馈使放大电路增益下降，但它可以（）通频带（）失真。

句型转换。

1. It's about five kilometers from my home to the school. (对划线部分提问)

    _____ is it from my home to the school?

2. My sister does her homework in the evening.(改为一般疑问句)

    _____ your sister _____ her homework in the evening?

3. I think Mr. Chen is in London. (改为否定句)

    I _____ Mr. Chen _____ in London.

4. The two boys want to travel. (改为同义句)

    The two boys want to _____.

5. He works in a factory. (对划线部分提问)

    _____ he _____?

Don't ____ a person only because he has failed in an examination. [ ]

A. look up

B. look down

C. look down on

D. look up to

FIDIC施工合同条件规定的指定分包商，其特点为( )。

A．由业主选定并管理

B．与承包商签订合同

C．其工程款从工程量清单中的工作内容项目内开支

D．承担不属于承包商应完成工作的施工

E．由承包商负责协调管理