Choose A, B, C, or D that best completes each unfinished sentence, substitutes the underlined part.
1. Many graffiti ______ without the permission of the owner of the wall.
2. You should be very ___________to your teachers for their help
3. You can ____________ your shorthand ability by taking notes in shorthand during lectures.
4. Scientists now understand ______________
5. "Which hat do you like best?" - "________________ ”
