16.Three hours ______ enough for us to finish the

16.Three hours ______ enough for us to finish the
task.
A.areB.hasC.isD.were 满分：2.5 分
17.Her answer is not acceptable,and ______.A.neither am IB.either is mineC.neither is mineD.mine is neither 满分：2.5 分
18.Never again ______ political office after his 1928
defeat for the presidency.
A.Alfred E.Smith
seriously soughtB.seriously Alfred E.
Smith soughtC.when did Alfred E.
Smith seriously seekD.did Alfred E.Smith
seriously seek 满分：2.5 分
19.The president,accompanied by his assistants,
______.
A.have arrivedB.are arrivingC.had arrivedD.has arrived 满分：2.5 分
20.______ iron has relatively few economical uses.A.Chemical pureB.Chemically pureC.Pure chemicalD.Purely chemical 满分：2.5 分