This is the 689th most frequent Chinese word.
同時
At the same time.
同时 is used to indicate two actions happening concurrently: working and listening to music.
他在工作的时候，同时听音乐。
He listens to music at the same time as working.
同时 is used here to express a time frame where two issues are being resolved together, emphasizing the simultaneity of the solution.
为了同时解决两个问题，我们设计了一个综合方案。
In order to address two problems at the same time, we designed an integrated plan.
同时 emphasizes her concurrent roles of being a student and a volunteer, stressing the coexistence of the two statuses.