You can only be sure of_________ you have at present; you cannot be sure of something _____ you might get in the future.

（2014年北京市西城区高三5月二模试题）30. — The professor gave a really good speech. — I suggest you _____ him some specific questions about his work experience.

1—I’m going to take partin the piano competition next week.— _____

Oh, you sound just like an American. — I still have trouble expressing myself.

Like some of my classmates，I cannot live up to my teachers’ expectations；________，I let them down