每年由于腐蚀造成的钢铁损失约占年产量的10~20%，金属的防腐十分重要。钢铁防腐方法有许多种，图—1与图—2是两个典型的例子。对其中原理的描述正确的是 （      ）

    It was a hot summer day. The sun was shining brightly and all could think of was1down with a scoop of my favorite ice cream. I decided to make a quick2to the newly opened ice cream parlor (冰淇淋店) close by for a mid-day3.

    As soon as I arrived there, I 4my ice cream in a fancy cone and asked the server to5two tubs of chocolate ice cream for folks at home.

    While waiting for my take-out, I was halfway through my icy treat and was enjoying the view of the two colorfully6ice cream flavors, sitting pretty one next to the other.

    Now that my to-go order was7, I headed to the payment counter to settle the bill. Surprisingly, the cashier had forgotten to8my ice cream,9only for the two tubs.

    The next few10passed by as I11between doing what was easy—clearing the bill and moving out, and doing what was right—12 the error. I knew if I didn't bring the error in the bill to his13, my ice cream would be charged against his14.

    That moment, my decision was made and I went and told him what he had 15. He looked at me in 16 and thanked me profusely for telling the error. Had it not been for my 17telling the error, he would have been 18. The smile of relief on his face made me smile, too.

    I came out of the ice cream parlor feeling really19about myself. I knew that day how wonderful it feels to do what is right20what is easy.

我们在竞争中必须遵守的基本准则是（   ） 

_____should we accept the unfair agreement．（   ）