30. More than 20 years ago he was badly wounded in the anti-Vietnam war. Since then he can only walk _____ an arm-chair .

29. Can you say _____ certain when he will come here?

28. He is too careful _____ his money; he never buys a drink for us.

27. You should write the first letter of the sentence _____ capital one.

26. I called _____ you last night, but you were out.

25. The train leaves at 6:00 p.m., so I have to be at the station ____ 5:40 p.m. at the least.

24. --- How did you go to work yesterday?
--- I went to work _____ my friend’s private car.

23. It is said that a bridge is being built _____ the river.

22. We will never forget this historical lesson written _____ blood.

21. He is very strict with others, but he is always blind _____ his own shortcomings.