Over years, scientists have made a great _____in the treatment of cancer.
| A．break-in | B．breakthrough | C．breakup | D．breakdown |
His house, for _______ he paid $10, 000, is now worth $50, 000.
| A．that | B．it | C．them | D．which |
.The buses, most of _______ were already full, were surrounded by an angry crowd.
| A．that | B．it | C．them | D．which |
It was not such a good dinner _______ she had promised us.
| A．like | B．that | C．which | D．as |
David is such a good boy _______ all the teachers like him.
| A．that | B．who | C．as | D．whom |
David is such a good boy _______ all the teachers like.
| A．that | B．who | C．as | D．whom |