变同义句。Peoplestillcouldn'tfindtheb
still couldn't find the boy. 能不能变 The boy couldn't be found. The boy hadn't be found. The boy was still missing.
意思都是差不多的,只是主谓不一样而已 The boy couldn't be found. The boy hadn't been found.(这里应该用完成时) The boy was still missing.