在于

1. depend on; rest with; be determined by

♦ 最后怎么决定~你。 The final decision rests with you.

2. lie in; consist in

♦ 战争的目的~消灭战争。 The aim of war is to eliminate war.

♦ 这项工程的问题不~进度, 而~质量。 The question of this project is one not of speed but of quality.