(1)(-7)+( )=21; (2)31+( )=-85;
(3)( )-(-21)=37; (4)( )-56=-40.
[主观题]填空。2/7=()/219/12=3/()5÷3=()/()=1又()/()
[主观题]填空。1/3+7/13=()5/7-2/7=()()-1/12=11/127/5-()=3/5
[单选题]3,7,13,21,31,( )。A.38B.41C.43D.49
[单选题]3,7,13,21,31,( )。A.38B.41C.43D.49
[单选题]3,7,13,21,31,( )。A.38B.41C.43D.49
[单选题]3,7,13,21,31,( )。A.38B.41C.43D.49
[单选题]3,7,13,21,31,( )。A.38B.41C.43D.49
[单选题]3,7,13,21,31,( )。A.38B.41C.43D.49
[单选题]3,7,13,21,31,( )。A.38B.41C.43D.49
[单选题]3,7,13,21,31,( )。A.38B.41C.43D.49