place.hold.er
n.（名词）One who holds an office or a place, especially:占位的人：处于某一职位或位置的人，尤指：One who acts as a deputy or a proxy.代理：做代理或委托的人One who holds an appointed office in a government.任职：在政府机构被委认某职的人In a mathematical or logical expression, a symbol that may be replaced by the name of any element of a set.占位符号：数学或逻辑用语，可以用其它元素的名称代替的符号In the decimal form of a number, a digit that is not significant.占位符号：在一个数的小数形式中，没有意义的数字
