projection: implies a jutting out especially at a sharp angle: those ~s along the wall are safety hazards.   (jut out突出伸出=to stick out，如a rock jutted out from the side of the bank岸边一块岩石突了出来，如a row of small windows jutted out from the roof有一排小窗户从房顶上突出来，如a jutting chin突出的下巴）    （project作为动词，1、预先计划计算估计to plan, calculate, or estimate something for the future, 如the bridge is projected to finish in the fall桥预计秋天完工，如the projected cost of the  project项目的预估开销  2、投放投影to send out，如projecting images on the screen向荧幕投影，如actors need to project their voices演员应大声说话  3、突出to stick out，如a balcony projects out over the seats below一个楼厅突出于下边座位的上方）


protrusion: suggests a thrusting out so that the extension seems an excrescence or a deformity: the bizarre ~s of a coral reef.   excrescence赘生物，词根和create相同，CRE表示to grow              thrust猛推猛塞猛冲，如he thrust at me with a knife他拿刀向我刺来, a thrusting movement冲刺动作，如he tends to thrust himself forward too much他这个人太好强(比喻义)


protuberance: implies a growing or swelling out from a surface in rounded form: a skin disease marked by warty ~s.     来自tube管子a long hollow pipe，通常是圆形    warty有疣的; 长着瘊子的


bulge: suggests an expansion or swelling of a surface caused by pressure withion or below: ~s soon appeared in the tile floor.   his eyes bulged他双眼凸出


projection突出: 表示突出，特别是角度尖锐的，protrusion突出: 表示突然的畸形赘生，protuberance圆突: 指圆形突出物，bulge突起: 表示受到内部或下部压力而突起


记忆方法: 1）首字母PPPB想成批评不平(这几个词都有贬义)<==突出           "突"是会意字，从穴从犬，本义是"犬从洞穴中突然窜出"，如突然突出突发突现冲突突兀唐突

         2）突出的意思是越过正常界限mean an extension beyond the normal line or surface.