On a map, south points ______________. [ ]
A. up
B. left
C. down
答案:C
桌裙的长度应以其底边离地面()为宜。
A.5C.m
B.10C.m
C.15C.m
D.20C.m
3,5,11,21,( )
A.32
B.30
C.31
D.35