------ He should have been warned of the danger.------_________ but he wouldn’t listen to me.A.So h

You should have been more patient ________ 怎么选择

【C17】A．must have beenB．may have beenC．could have beenD．should have been

He should have been a young officer.

I have no idea who stole his wallet. It _____anyone.A. must have beenB. should have been

He was warned______he should make the same mistake again.A．ifB．givenC．lestD．unless

Scientists have been working hard to warn people_