—You may find the key to the maths problem on page 107. —Ah, it’s so simple. I wonder why I _of that.
32. She is not always so friendly. I wonder what she________.
31. The farmers wondered if vegetables bring in______crops.
30. This dictionary is of great use, which can help you_________many problems about words and idioms.
29. The________you sign your name can tell experts a lot about you.
28. Hello, you_______5678234, I’m sorry but I am unable to answer your questions right now.