名词是signature
He traced his signature laboriously.
他吃力地签上自己的名字.
On (ie As a result of) further examination it was found that the signature was not genuine.
经过进一步的调查发现签名不是真迹.
This document bore his signature.
这份文件上有他的签名.
sign是动词
Should I sign my name in pencil or ink?
我用铅笔还是用钢笔签字?