Ring groove inserts are occasionally used on aluminum alloy piston to_______.A.reduce the

A．They insert advertisements when the movies are near the most appealing part.B．They g

We can hear mobile phone ring no matter where we are and it is quite annoying sometimes. W

While I am on holiday, ring me at my hotel only if there are any ___ message for me.A、

I catch cold 【now and then】.A. alwaysB. occasiona

I catch cold 【now and then】.A. alwaysB. occasiona

大沟（major groove)和小沟（minor groove)