It's the bill for assembling your play structure.

拼装游乐器材的账单。

The blades must be shipped in one  piece, which requires enormous ports, vessels and cranes capable of assembling  these structures in the middle of the ocean.

叶片必须整块运输, 这需要巨大的港口、船只和起重机, 这些港口、船只和起重机能够在海洋中央组装这些结构。

You might imagine micro robots as agents to repair or assemble small structures or machines in industry, or as surgical assistants to clear clogged arteries, to stop internal bleeding, or to eliminate cancerous tumors.

你可以把微型机器人想象成在工业中修理或组装小型结构或机器的代理人，或者作为外科手术的助手，清理堵塞的动脉，阻止内出血，或消除癌性肿瘤。