Health is important for us teenagers, so we should eat more vegetables such as to keep healthy.
A:tomatoes and potatoes
B:tomatos and potatos
C: tomatos and potatoes
用一个平面去截一个圆柱:
(1)所得截面可能是三角形吗?
(2)如果能得到正方形的截面,那么圆柱的底面半径和高有什么关系?
世界上最长的山脉是( )
为使嫁接果树成活,嫁接过程首先要注意( )
现有一由Na2SO4、Na2SO3、Na2S组成的混和物,经测定硫的质量分数为2 5.6%,则此混合物中氧元素的质量分数应为( )