In the book Brfore We Were Free:

Who are the SIM? According to Chucha, what do they do?

Explanation:

Chucha is Anita’s family’s housekeeper, who is originally from Haiti. She’s been with the family since Papi was a baby and the family trusts her with everything. Chucha sleeps in a coffin to prepare for the next life, and she made a promise to some unknown person or entity that she’d wear nothing but purple. She also has dreams that tell her the future. All of this gives her a mystical and sometimes frightening air. Chucha is fond of proverbs and sayings, many of which Anita adopts as her own as she comes to understand their value. She also relies heavily on Chucha for comfort—and for information as the situation in the Dominican Republic gets increasingly dire and Chucha proves to be one of the only adults who will tell her things, albeit by speaking in riddles. Chucha prepares Anita cryptically for the possibility that she will have to leave the country and that Papi might die. And when Anita gets her period, Chucha is the person she immediately tells. Following Trujillo’s assassination, when Papi is arrested and Mami and Anita go into hiding at the Mancinis’ house, Chucha takes a job at a local grocery store. From there, though she isn’t supposed to know where Anita is, she manages to pass messages to Anita to prepare her for the next stage of her journey. Though it’s unclear by the end of the novel if Anita is going to see Chucha again, Anita thinks often of Chucha’s sayings and spirituality. As she does, Anita is able to vow to try to be happy again.

Chucha Quotes in Before We Were

The S.I.M. are El Jefe's workers and they raid peoples house for him to make sure they aren't planning or hiding anything that needs to be found. Sometimes they hurt people just because El Jefe told them to do it.

Anita finds Chucha, who says the men are SIM, the secret police. According to her, they “investigate" everyone. So, according to Chucha, what the SiM do is they investigate everyone and do other secret police work.

Explanation: Hope this helps

#1  sara was always tasked with selecting birthday presents for her friends and family because everyone admired her  impeccable taste. 

impeccable (adj): perfect, flawless

#2  they moved to the united states many years ago, but their  insular  attitudes made it difficult for them to socialize. 

insular (adj): isolated; separate

#3  the professor explained the  semantic  relationship between the two nouns used in the sentence. 

semantic (adj): related to words or the meanings of words 

happy to : )