计算:-2xy2•(-3xy)2=______.
原式=-2xy2•9x2y2=-18x3y4.
故答案为:-18x3y4
Good shoes, clothes and a backpack are the basic______ you need for your hiking.
A.equipment
B.instrument
C.tools
D.fixings
用2个6、2个4和4个0可以组成一个8位数,写出符合下列要求的数.
(1)一个零也不读:______.
(2)只读一个零:______.
(3)读两个零:______.
(4)读三个零:______.
(5)最大的8位数:______.
(6)最小的8位数:______.