题目

已知：MN为⊙O的直径，OE为⊙O的半径，AB、CH是⊙O的两条弦，AB⊥OE于点D，CH⊥MN于点K，连接HN、HE，HE与MN交于点P． （1）如图1，若AB与CH交于点F，求证：∠HFB＝2∠EHN； （2）如图2，连接ME、OA，OA与ME交于点Q，若OA⊥ME，∠EON＝4∠CHN，求证：MP＝AB； （3）如图3，在（2）的条件下，连接OC、BC、AH，OC与EH交于点G，AH与MN交于点R，连接RG，若HK：ME＝2：3，BC＝，求RG的长．It was so noisy in the dining room that only by shouting ____ to make himself heard.A．he has been ableB．has he been ableC．was he ableD．he was able