 Rammed @-@ earth walls during this time were tapered : the thickness of the wall is greatest at the base and decreases steadily with increasing height , as detailed in Li Jie 's book . 
 Rammed @-@ earth walls during this time <a href='uninflect' title='1'><mark>were</mark></a> tapered : the thickness of the wall is greatest at the base and <a href='uninflect' title='2'><mark>decreases</mark></a> steadily with increasing height , as detailed in Li Jie <a href='null_genetive' title='3'><mark>'s</mark></a>book . 
Rammed @-@ earth walls during this time was tapered : the thickness of the wall is greatest at da base and decrease steadily with increasing height , as detailed in Li Jie  book .