现有若干圆环,它的外直径5厘米,环宽0.5厘米,将它们(如图)扣在一起,拉紧后测其长度.
(1)根据规律,则2个圆环拉紧后的长度是____ 厘米,10个圆环拉紧后的长度是____ 厘米.
(2)若拉紧后的长度是77厘米,它由____ 个环扣成的.
(3)设环的个数为a,拉紧后总长为S,请你用一个关系式表示你发现的规律.____ .
You should try ____ (improve) your spoken English to make yourself understood.
A number of children ________ parents had died in the quake were sent to live with families in other cities.
判断.
两个非0的连续自然数的最小公倍数就是它们的积.