由题意,知-1a=-2,
去分母得:-1=-2a,
解得,a=12.
经检验,a=12是原方程的解.
故选B.
硬水和软水的本质区别是( )
A.硬水浑浊,软水澄清
B.硬水含杂质多,软水含杂质少
C.硬水不是纯净物,软水是纯净物
D.硬水中含有较多的可溶性钙镁化合物,软水不含或含少量的可溶性钙镁化合物
31. The engine of the bus was out of order and the bad weather ______ the worries of the passengers.
A.added up
B.added to
C.resulted from
D.made of