9. Which of the following sentences uses an abstract noun? A. Dirt stuck to the Heatsink Processor, VGA, and Chipset can hinder the fan cooling process. B. Because the dirt-covered heatsink causes the airflow not to hit the parts directly. C. Dust that is attached and allowed to accumulate on the motherboard can cause damage to the components inside. D. Sooner or later if not cleaned, this can cause a short circuit on the motherboard. E. From now on try to clean your computer regularly. 10. "The letters on the keyboard also become difficult to press, and even if you can press them, the letters do not appear on the screen." The word in bold has the synonym as .... A. release B. unhand C. unlock D. free E. hold down​