Lofty derricks dot the landscape in an oil field.

高耸的井架点缀着油田的景色。

Derricks are scattered here and there on the boundless plain.

在一望无际的原野上散布着一座座井架。

Capacity of derricks 20tonnes.

船吊吊载能力20吨。

Let's keep away from the derricks.

咱们离吊杆远一点走。

Keep safe working load of derricks.

让吊杆在安全负荷下工作。