Only a few are in use, and they are all operated by specialized heavy-lift companies.

只有少数在使用中，并且全部由专业的重型起重公司运营。

A specialized company that carries this out is a market research firm.

进行这项工作的专业公司是市场调查公司。

In the last few years, however, as more and more women have entered the labour force, alumni reunions are increasingly being planned by specialized companies rather than by part-time volunteers.

然而，在过去几年中， 随着越来越多的女性进入劳动力市场，校友聚会越来越多地由专业公司而不是兼职志愿者来策划。