I wish I what is happening there in his room. [ ]
A. know
B.known
C.knew
D.should know
答案:C
找规律,按规律填数.
1×3+1=4=2×2…第一式
3×5+1=16=4×4…第二式
5×7+1=36=6×6…第三式
…
25×27+1=( )=( )×( )…第19式
( )×( )+1=( )=100×100…第50式
( )×( )+1=( )=( )×( )…第60式.
一般在渗透性较弱的沙性母质上灰化土发育最快。