非限定性定语从句引导的句子,谓语是什么形式呢?不可以用其他时态么比如这道题:Wal-Mart,which is one of the largest American supermarket chains,_____ some of its store open 24 hours on Mondays through Saturdays. 只能填keeps么?其他时态都不行吗?
which is 是一般现在时,这里讲的是一般情况。所以用现在时。