One who or that which works or acts.

工作者；操作者。

One who is employed in a telephone exchange to make connections between lines.

电话接线生。

One that is smooth and highly expert in some line.

精通的人；善于经营的人。

A dealer or speculator in stocks or commodities.

炒股票者；做投机生意的人。

One that performs surgical operations.

执行外科手术者。

Symbol indicating a mathematical process to be performed.

【数】运算符号(如＋、－、×、÷等)。

A chromosomal region that triggers formation of messenger RNA by one or more structural genes and is itself subject to inhibition by a genetic repressor.

操纵基因(负责调节及激起结构基因活动的染色体区域)(=operator gene)。