Answer:
1. Hank was an opportunist, <em><u>taking advantage</u></em> of every possible angle.
2. My mother was candid, <em><u>honestly</u></em><em> </em>sharing her ideas on the subject.
3. The stupendous actor attracted everyone's attention because he was <em><u>good</u></em>.
4. President Duterte's policies <em><u>changed </u></em>society, catalysts for improved living around the country.
5. Peter was <em><u>likely </u></em>to be late, and apt to forget necessary supplies as well.
Explanation:
In the given sentences, the words in bold are the words that most define the whole sentence. And in the need to underline the words that help us to understand the bolded words, we are, in a way, looking for the words synonymous or give the same meaning.
In sentence 1, the bolded word "opportunist" is used for a person who takes advantage of any situation for his/her own good.
Sentence 2's "candid" refers to someone who is truthful or open about anything and everything.
The word "stupendous" in sentence 3 refers to someone who is good, remarkable, extraordinary in the things he does.
Sentence 4 has the word "catalysts" which is used for things that help change, induce, or encourage.
And in sentence 5, we have "apt" which is another word for liable, likely, most probably, etc.