当分母x-9=0,
即x=9时,分式1x-9无意义.
故答案为:9.
在水源的某处排放污染物,就会污染整个水源,主要原因是 [ ]
A.分子很小
B.分子是可分的
C.分子之间有间隔
D.分子在不断地运动
— What were you doing at this time yesterday?
— I _______ basketball with my friends. [ ]
A. was playing
B. had played
C. have played
D. played