If someone has an accident and can no longer walk, scientists might be able to use stem cells to ___ the damaged cells and allow that person to walk again.

A．rescue

B．remove

C．reserve

D．replace

《长恨歌》和《琵琶行》是两首著名的叙事诗，它们的作者是*

A．王安石、白居易

B．李清照、白居易

C．李清照、自居易

D．自居易、白居易