who were the telephone invented by

问题描述:

who were the telephone invented by
这个句子对,还是
whom were the telephone invented by
by后不是加宾语么,那应该是第二个了?但是第一个句子是教科书上出现的

were->was
Who/Whom was the telephone invented by?
by who/whom都是对的,要知道who可替代whom(而whom不可替代who).
who也可以作宾语.