A:绝大多数无机盐以化合物的形式存在
B:山羊的血液中如果Ca2+的含量过低,就会出现抽搐
C:无机盐离子对维持血浆的正常浓度和酸碱平衡等有重要作用
D:镁是构成叶绿素的必需成分,植物缺乏镁时会导致叶片发黄
如图是英国各行业就业人数占总就业人数的比例变化数据表,这反映出工业革命加快了英国( )
请根据句意从方框中选择合适的单词,并用其适当形式填空,使句子通顺。____ This shop sells all kinds of ▲ from different countries.____ I hear that her uncle has bought a new flat in the city centre ▲ .____ Jack won the ▲ prize in the school reading contest and he felt very excited.____ He had to make a ▲ between staying with his parents and going abroad. ____ You know Mike’s hobby is playing football, but ▲ is collecting stamps.
阅读下列材料,回答问题材料一 春秋战国以来,社会急剧变化,许多问题亟待解决,各学派纷纷著书立说,发表意见,并互相辩论,形成了“百家争鸣”的学术繁荣的局面。材料二 泉城广场齐鲁文化长廊中有12尊山东历史名人雕像,其中有四人是我国春秋战国时期著名的思想家,他们是孔丘、孙武、墨翟、孟轲。
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 ____。