time-consuming

adj.耗费时间的

This learning period can eat up time and cause frustration. 学习期间可能耗费时间，而且令人灰心。

The meter should show the progress relative to the total time the process will consume rather than the total size of the process. 进度表应该显示相对整个过程所耗费时间的进度，而不是相对整个过程规模的进度。