In some cases, colleges and universities might have to change their training programs, adding another layer of difficulty.
在某些情况下，学院和大学可能不得不改变他们的培训计划，这增加了计划的难度。
2
These layers and be added or removed dynamically and you can change each layer as it has a track that lets you change it as a function of time by inserting keys at certain frames in the track.
Since independence was proclaimed by the son of the Portuguese king, Brazil has been adding layer upon layer of change rather than sweeping away the old and starting afresh.