The expression on his face suggests he ________ have failed in the competition.—I guess so. It’s not easy after all.

Did you visit the famous cultural relics last month?—No,we _________ it,but we spent too much time shopping.

Only when he started to explainthe reason for this.[ ]

He should________his attention________the main problems. [ ]

The reason why he failed is ______ he was too careless