solid45建模是怎么建的

fini
/clear

/UNITS,SI
/FILNAME,mdm,1
/TITLE,modaomen
/PREP7
!材料
ET,1,solid45    

!!!   C50
mp,ex,1,3.45e10
mp,prxy,1,0.2
mp,dens,1,2600

!!主梁截面特性
r,1 , 3.45e10,3.45e10，3.45e10，0.2，0.2,0.2      

              
n,1,-1,0,-1
n,2,-1,0,1
n,3,1,0,1
n,4,1,0,-1
n,5,-5,-6,-7
n,6,-5,-6,-5
n,7,-3,-6,-5
n,8,-3,-6,-7

TYPE,1
MAT,1
REAL,1 

E,1,2,3,4,5,6,7,8

/SOL
ATYPE,0
NLGEOM,1

这是我的命令，为什么没法建出来呢