_________ is known to us all is that the old scientist, for ___________ life was hard in the past, still works very hard in his eighties.
A．As; whom B．What; whom C．As; whose D．What; whose
_________ is known to us all is that the old scientist, for ___________ life was hard in the past, still works very hard in his eighties.
A．As; whom B．What; whom C．As; whose D．What; whose