I think the answer is c...
1.A selfish person is incapable <em><u>of</u></em> true friendship.
2.How much time do you spend <em><u>on</u></em> homework?
3.Good friendship should be based <em><u>on </u></em>mutual understanding.
4.Do you keep in touch <em><u>with</u></em> any school friends?
5.Some adults have a total lack <em><u>of</u></em> sympathy <em><u>for</u></em> young people.
6.She had been briefly acquainted <em><u>with</u></em> him more than 20 years earlier.
7.Some people take <em><u>up</u></em> interest with enthusiasm, but they are soon tired <em><u>of</u></em> it.
8.She has learnt English for three years, and she is good <em><u>at</u></em> English now.
9.I wish Carol would take a holiday. It would be good <em><u>for</u></em> her health.
10.Mary always takes care <em><u>of</u></em> her children carefully.
11.It was very kind <em><u>of</u></em> you to help me with that difficult work.
12.You were very kind <em><u>to</u></em> me when I asked you for some help.
<span>It's that they symbolize selfless giving </span>
Answer:
21: C.) while being stranded in the desert
22: C.) He put on food and edible supplies.
23: A.) sarcastic
24: C.) I beat myself up having been ungrateful about being alone because I longed to return to where I was before. (Not sure)
25.) A.) He misses the life he had before embarking on his journey (Most logical answer but B is possible)