若m=$\frac{\sqrt{2}}{2}$×（﹣2），则有（　　）

“五十六个民族，五十六枝花，五十六个兄弟姐妹是一家…”，这首歌曲唱出了我国各族人民的心声．我国少数民族中，人口最多的是（    ）

如图，斜面上有a、b、c、d四个点，ab=bc=cd，从a点以初速度v₀水平抛出一个小球，它落在斜面上的b点，此时的速度方向与斜面之间的夹角为θ；若小球从a点以初速度 $\sqrt{2}$ V₀水平抛出，不计空气阻力，则小球（   ）

    Chinese writing began thousands of years ago. According ____ an ancient story, a man named Cang Jie invented Chinese writing. One winter day while he was hunting, he saw the ____(track) of animals in the snow and ____(observe) that the appearance of each one was different. Then ____he got was that he could use different shapes ____(represent) different objects. The ____(one) Chinese characters were drawings of physical objects. Some characters ____(simplify) and others have been made ____(difficult) over time.____, as a whole, the characters have ____(gradual) developed from drawings into standard forms.

下列各物质中，按熔点由低到高排列正确的是(　　)