A:肤浅(fū)竞相诽谤(fěi)忌恨(jì)繁芜丛杂(wú)
B:诅咒(zhòu)豁然开朗(huò)领域(yù)得心应手(yīng)
C:诬蔑(miè)卓有成效(zhuó)衷心(zhōng)非同寻常(xūn)
D:要素(yào)永垂不朽(xiǔ)
如图,已知以直角梯形ABCD的腰CD为直径的半圆O与梯形上底AD、下底BC以及腰AB均相切,切点分别是D,C,E.若半圆O的半径为2,梯形的腰AB为5,则该梯形的周长是 ____。
Who is ____, your father or your mother? (busy)