A:实验室制取硝基苯
B:实验室分馏石油
C:食盐的蒸发
D:溴乙烷和NaOH水溶液加热反应
a1+a22≥a1a2a1+a2+a33≥a1a2a33a1+a2+a3+a44≥a1a2a3a44⋯⋯⋯
照此规律,当 n∈N+(n≥2) 时, a1+a2+a3+⋯+ann≥ ____.
— ________ is your new bike?
— I ________ about 900 yuan for it.
Tom and Mike are good friends. ________ often help each other