Many buildings in the city need repairing, but the one first is the library.
It doesn’t make a(an)_______to me whether you go or stay.
How did it______ that humans speak so many different languages?
Eric was well prepared for the computer test so that he could be positive about passing it on his first________.
The dead rate is _____ pigs and recovery usually ______ within 7-10 days. A low in; occurs B. rich in;happens C. high in; came about D. poor in;took place
_____ three influenza type A virus subtypes(子类型) have been found in pigs.