At the end of last class, the English teacher requested that the homework this morning.
A．handed in. B．be handed in
C．would be handed in. D．had handed in.
A number of methods been used, but the number of animals still small in the forest.
A．have; is B．has; is
C．have; are D．has; are
If ,the experiment will be successful.
A．do carefully. B．did carefully.
C．carefully done. D．doing carefully.
such heavy pollution already, It may now be too late to clean up the river.
A．Suffering. B．Having suffered. C．To suffer. D．Suffered.
The spokesman didn’t make clear why the president failed to attend the conference.
A．this. B．that. C．it. D．what.
One may never know the of knowledge without being educated.
A．power. B．force. C．energy. D．strength.
