—Why does the lake smell terrible?
—Because large quantities of water_______________.
A.have polluted B.is being polluted
C.has been polluted D.have been polluted
One-third of the country____covered with trees and the majority of the citizens_______black people.
A is；are B is；is C.are；are D.are；is
Was it not until you began to work —— how much time you had wasted?
A.did you realize B.that you realized C.did you not realize D.that you didn’t realize
Peter has gone to Beijing, but I’m wondering why he ________ in such a hurry.
A. left B. has left C. leaves D. was leaving
After studying mass of data，they drew a conclusion
________China is still a developing country.
A.that B.which C.／ D.where
Along with the letter was his promise he would visit me the New Year.
A.which B.that C.what D.whether
