Here are the appropriate words to fill in the blanks based on the given hints:

51. If you try to work effectively for one year, you will be able to get a **promotion**. (promote)
52. In some parts of the world, people are still divided into different **societal** classes. (society)
53. Your son is rather uncommunicative. You should encourage him to **socialize** more. (society)
54. The final competition included the **representation** of three classes. (represent)
55. A small percentage of TV advertising includes **announcements** about local community activities. (announce)
56. The teacher’s comments are designed to help improve your **knowledge** and **understanding**. (know/understand)
57. The company has decided to withdraw from some of its **sponsorships**. (sponsor)
58. A voluntary funded agency, UNICEF relies on contributions from governments and private **donors**. (donate)
59. **Organ donation** is allowing doctors to use an organ from your body after your death in order to save a sick person’s life. (donate)
60. Many local people give money as a **donation** to the **disadvantaged** children in this area. They are kind **donors**. (donate, advantage, donate)
61. Carbon dioxide is a type of **emission** which is believed to be damaging our environment by causing global warming. (emit)
62. Vaccination has been considered among the most important **inventions** in medicine. (invent)
63. We are looking for camp helpers who are hard-working, **energetic**, and able to organize activities for young children. (energy)
64. We’re seeking the **most talented** musician to join our entertainment company. (talent)
65. The **handicapped** have to suffer from a serious physical or mental disability. (handicap)
66. Volunteers can work with many **disabled** children who were harmed by Agent Orange in childcare centers. (able)
67. I shall do the job to the best of my **ability**. (able)
68. It is important that **applicants** read the guidance before they apply. (apply)
69. Mary wrote a letter of **application** to Microsoft yesterday after seeing their advertisement in the morning. (apply)
70. Scientists are looking for an **effective** way to reduce energy consumption. (effect)
71. The department needs three more computers in order to work most **effectively**. (effect)
72. The Club has **organized** many volunteering activities for all students to participate. (organize)
73. He has just found a job advertisement from a non-governmental **organization**. (organize)
74. Nowadays more and more teenagers and young people are getting involved in **charitable** activities. (charitable)
75. You can now learn a new language in the **convenience** of your own home. (convenient)
76. The most **innovative** design will be awarded a prize. (innovate)
77. Do you feel **hopeful** about the result? - Yes, I think I performed well at the interview. (hope)
78. A digital camera is more **economical** than a film camera since you don’t have to buy rolls of films. (economy)

If you need further assistance, feel free to ask!