4．(2013·安阳高二质检)Let's make good use of energy and________wasting natural resources.

　　A．keep on B．result in

　　C．be opposed to D．appeal to

　　5．The Chinese government is preventing H7N9 flu from spreading out________.

　　A．at a cost B．at the cost

　　C．at all costs D．at cost

　　6．When the thief________to enter the room，a cough frightened him away.

　　A．sought B．risked

　　C．ought D．imagined

　　7．It has been revealed that some government leaders________their authority and position to get illegal profits for themselves.

　　A．employ B．take

　　C．abuse D．overlook

　　8．After the quarrel，I tried all my best to remove the misunderstanding between us，but all my efforts seemed________.

　　A．in vain B．in case

　　C．in time D．in trouble

　　9．Drilling for oil poses a________to wildlife in the area.

　　A．threat B．threatening

　　C．threaten D．confidence

　　10．A good teacher should leave some time for the students to________the knowledge.

　　A．introduce B．receive

　　C．digest D．expect

　　11．The result________his theory，so we had to do the experiment again.

　　A．contradicted B．seemed

　　C．proved D．disagreed

12．It is not a good habit to state your opinion________and you'd better think it