若方程(k2-1)x2+(k+1)x+(k-7)y=k+2为二元一次方程,则k=( )。
1
A ___school boy, LiLida, first tried to swim across the Qiongzhou Channel in June, 2000.
A.12 - year old
B.12 - years - old
C.12 - year- old
D.12 years old
半侧空间忽视的病人一侧初级视觉皮层严重受损因而无法接收视觉信号。