id结尾的单词四个字母

　　It is treated with acid before being analysed.

　　对它先用酸处理再进行分析。

　　Litmus paper turns red in the presence of an acid.

　　石蕊试纸遇到酸就变红。

　　There are serious problems of land degradation in some arid zones.

　　在一些干旱地带存在严重的土地退化问题。

　　He was avid for more information.

　　他渴望知道更多信息。

　　Many canals were built along map grid lines.

　　很多运河是按照地图上的坐标线开凿的。

　　He has laid himself wide open to political attack.

　　他在政治上已经处于极易受到攻击的境地。