A.
B.
C.1
D.2
[单选题]设,D:x2+y2≤a2,则a为( )。A.B.C.1D.2
[单选题]设,D:x2+y2≤a2,则a为( )。A.B.C.1D.2
[单选题]设,D:x2+y2≤a2,则a为( )。A.B.C.1D.2
[单选题]设,D:x2+y2≤a2,则a为( )。A.B.C.1D.2
[单选题]设,D:x2+y2≤a2,则a为( )。A.B.C.1D.2
[单选题]设,D:x2+y2≤a2,则a为( )。A.B.C.1D.2
[单选题]设,D:x2+y2≤a2,则a为( )。A.B.C.1D.2
[单选题]设,D:x2+y2≤a2,则a为( )。A.B.C.1D.2
[单选题]设,D:x2+y2≤a2,则a为( )。A.B.C.1D.2
[单选题]设,D:x2+y2≤a2,则a为( )。A.B.C.1D.2