题目

Areyou afraid that your friend would laugh at you, or would not understand whatyou are (经历)? 答案：【1】going【2】through 如图，在三棱锥P－ABC中，AB⊥BC，AB＝BC，点O、D分别是AC、PC的中点，OP⊥平面ABC．求证：OD∥平面PAB．