铜墙铁壁

Explanation: The original metaphor is very strong defense, not destroyed. Also be used together. 　　Usage: Joint type; as subject, object; with compliment 　　Source: Yuan Anonymous "Xie Jinwu" wedge: "This baby go with him impregnable fortress, is not afraid of not split down to him." 　　Examples: Song Jiang cited the front from the troops, turned to look back I wish Chuang Longgang alone, the back is ~, to be thorough. (Ming Shinai "Tales of" forty-eighth back) 　　Riddle: Safe Thesaurus:  strongly fortified, (of a city, military positon, etc.) impregnable, have a clear [good] conscience, high walls and deep moat-a defended city, Strict bulwark, golden city city moat filled with boiling water&mdash, Tie Bitongqiang, bosom broad and level, peace of conscience, feel no shame before God, pleased with oneself, triumphant, perk Antonym Group:  utterly devoid of conscience; be entirely heartless, 2 Peach 3 persons, Second, killing three persons Peach, Yiyifayi, play off one foreign power against another (so as to prevent them from, Yiyizhiyi, do things offensive to God and reason, He that has a great nose thinks everybody is speaking of it., murder by means of another's aword, A guilty conscience is a self -accuser., like an ant on a hot pan, be [sit, stand, walk] on [upon] thorns, _set_ insomnia with restlessness, fidget, consume, Large Gourmet Kitchen, be on the anxious seat, absence, willies, overlook, Wavering Shook, emotions which churn inside like the flow and ebb of tide accident, Xindanjulie, be in a fidget, wolf, Lianjiutanhua, Wine lovers love to spend, be struck with panic, timorous agitation, heebie-jeebies, at a loss what to do, arrear, Landless dine, can find no place to hide oneself for shame, nowhere shelter oneself, nowhere take cover, Wusuocuoshou, at a loss what to do, stab sb. in the back, dehumanization, fidget, care, Kuang He booze, raven, preoccupation, mind stupefaction, swoon, delay, fool around, show appearance and give soul to, Thoughtfully, loaf, Thief scared, with a guilty conscience, Drink ears flush from excitement, Fond, tipsy, Drunk food eat, have a guilty conscience, One could hear a pin drop., too sad to eat, have no appetite for food, Hunfeipoyang, Wits