英语中,不定式作表语时,可以省略系动词吗?还有其他省略系动词的情况吗?也举些例子.

英语中,省略系动词通常是在做后置定语的时候,将原先的定语从句的表语变成后置定语或插入语,从而使句子简单.省略系动词的同时必须也省略主语（关系代词）.例如 The man who is in black hat is my father. 变成 The man in black hat is my father. (in black hat作后置定语). 或 The man, in black hat, is my father. (in black hat作插入语)
至于什么成分充当表语无所谓.但不定式作后置定语的情况确实很少见,原因是不定式也很少作定语从句里的表语.下面这句话虽然没有语法错误,但很少这么说： The man who is to solve the problem is my father. 也可变成 The man to solve the problem is my father. 由于不定式有表即将做某事的意思,常用的说法是加一个going,使之成为将来时,The man who is going to solve the problem is my father. 此时一般不省略who is.