Stairs whose primary structure is a door shall be covered under the appropriate topic. Includes items such as structure, actuating mechanisms and controls, handrails, etc.

A. Clear the pipes in order to remove corrosion.

B. Wash the pipes so as to remove dust.

C. Flush the pipes to remove contamination.

A. 工作准备总是第一个步骤，收尾或收工是最后一个步骤是

B. 工作准备总是第一个步骤，收尾或收工是接下来的步骤

C. 第一个步骤有时是工作准备，收尾或收工是接下来的步骤

A. In order to locate lower margins of safety components and areas, current records were reviewed.

B. To find components and areas where have showed lower margins of safety, existing results were examined.

C. Existing analyses were reviewed to identify components and areas that may have exhibited lower margins of safety.

A. This method is used widely in plotting vectors for navigation problems on a chart.

B. Plotting factors for navigation problems on a chart is a widely used method.

C. Drawing factors for navigation problems on a chart is a widely used method.

A. 附录应显示系统数据所在的章或子章。

B. 目录应显示章或子章以及系统路径所在的位置。

C. 索引应显示系统电路所在的章或子章。

A. Turn ADF 1 to unknown frequency.

B. Tune ADF 1 to a known frequency.

C. Tune VOR 1 to a known channel.

A. 门是由碳纤维复合塑料制成的。

B. 门的主要成分是碳纤维复合材料。

C. 门是由碳纤维增强塑料制成的。

A. There is always room for improvement in the effort to describe these steps.

B. It is impossible to list all the steps because there is always room for improvement.

C. Describing these steps need to do a lot of work.

A. If you find metal particles in the reservoir, find their source and repair the broken part.

B. If you find metal particles in the pump, find their source and repair the defective part.

C. If you find material particles in the pump, find their source and repair the damaged part.

A. If an AC circuit consists of resistance only, the value of the impedance is the same as the resistance.

B. If an AC circuit consists of impedance only, the value of the capacitance is the same as the impedance.

C. If an DC circuit has capacitance only, the value of the resistance is the same as the capacitance.