因为a和b都为不是0的自然数，且a=7b．
所以a与b的最大公因数是b；
故选：C．
—What about the concert last night?
—___ I might as well have stayed at home and watched TV.
A．It couldn’t have been any better.
B．It couldn’t have been any worse.
C．It was the best one.
D．There was no better one.
无阀滤池的自动反冲洗是根据（）的原理形成的。
