弄清（楚）

gain a clear understanding of; fully grasp the meaning of;get a clear idea of;become clear on;clarify
～大是大非 distinguish between right and wrong on major issues/～情况size up a situation; familiarize oneself with a situation/～事实set facts straight;get a clear picture of facts/～是非distinguish right from wrong; clarify what is right and what is wrong/～问题straighten things out