A landmark(里程碑) in the history of science was made by a photo _______ was taken on April 10th about the black hole in a faraway galaxy(星系).( )
A. |
who |
B. |
which |
C. |
what |
D. |
when |
A landmark(里程碑) in the history of science was made by a photo _______ was taken on April 10th about the black hole in a faraway galaxy(星系).( )
A. |
who |
B. |
which |
C. |
what |
D. |
when |