方程(a-1)x-y+2a+1="0" (a∈R) 所表示的直线
A.恒过定点(-2,3)
B.恒过定点(2,3)
C.恒过点(-2,3)和点(2,3)
D.都是平行直线
答案:A
A common question that people ask a story writer is whether or not he has experienced what he has written about.
A.fiction
B.science
C.imaginary
D.literary
影响药物溶解度的因素有()
A.温度
B.溶剂
C.药物的性质
D.粒子大小
E.压力