Here are the correct answers for each of the sentences:

31. Will you be taking my previous experience into **B) account** when you fix my salary?

32. If it wasn’t an accident, he must have done it on **B) purpose**.

33. Most things are now mass-produced rather than **A) hand-made**.

34. The office lifts are out of **B) order** again.

35. Let me know if any difficulties **B) arise**.

So, the final answers are: 31-B, 32-B, 33-A, 34-B, 35-B.