There is no doubt ____ we will host the2010 World Expo successfully

下列各句中，标点符号使用正确的一项是（ ）

Tom，you’ve got an A in the final English exam.Congratulations!—Thanks.But I never thought the result came out so fast.The papers________when I left the teacher’s office just now

look rather down today. —______ to board the 4:20 flight, you know, I dared not close my eyes.

Mr. Smith, Can you give us some advice onhow to learn English well’–Remember, Nothing can be learned well______hard work.