At one time we had about eight people here who did nothing but__into family history 为什么填researc如果填researching行吗?

问题描述:

At one time we had about eight people here who did nothing but__into family history 为什么填researc
如果填researching行吗?

是个词组:do nothing but do
所以是原型

(had been )written

do nothing but doing sth 除了做某事,其他什么都没做.应该是对的吧