下列实验操作正确或能够达到目的是（ ）
A．
除去氯气中的杂质
B．
分离水和酒精
C．
吸收尾气中的氨气并防倒吸
D．
比较纯碱和小苏打热稳定性
答案：D
（x﹣1）（2x+3）
He was regarded as such a _____ student that all of the teachers believed that his future
would be bright. [ ]
A. bad
B. stupid
C. poor
D. gifted
