集合，集会的意思。When people assemble or when someone assembles them, they come together in a group, usually for a particular purpose such as a meeting.
The assembled multitude cheered and whistled as the political leaders arrived. 当政治领袖到达的时候，聚集的人群欢呼起来,并吹起了口哨。
集合，组装，装配的意思。To assemble something means to collect it together or to fit the different parts of it together.
She had been trying to assemble the bomb when it went off in her arms…
He is assembling evidence concerning a murder. 他正在收集一桩谋杀案的证据。