判断题：水杨酸分光光度法测定水中铵时，酸度和碱度过高都会干扰显色化合物的形成。A．正确B．错误

彩陶成就最突出的是黄河流域的（）文化和马家窑文化。

Don't tell me what to do!

Economists study the way a society uses scarce resources such as land, labor ...

Fred was such a hardworking student that he soon came out first in the class.

Great writers are those who not only have great thoughts but also express the...