They are called virtual particles in order to distinguish them from real particles，whose lifetimes are not constrained in the same way，and which can be detected.
它们被称为“虚粒子”(virtual particle)，以便与实粒子(real particle)区分开来，而实粒子则不会以这种方式受到制约，并且其存在可得以测定。
难句类型：复杂修饰、插入语
难点解析：本句的怪异在于：real particles后面跟着两个定语从句，都是同时修饰real particles的，而且两个从句之间不用逗号隔开，却又加上and连接，令人一眼看上去极不习惯。
结构划分：They are called /virtual particles /in order to /distinguish them from real particles，/whose lifetimes /are not constrained /in the same way，/and which can be detected.
