In this task, based on the given context word, you are asked to create a pair of sentences each containing a blank (_). The sentence pair should look similar and should be about two different persons (PersonX and PersonY). Additionally, the two sentences must be different in terms of trigger words (e.g., "sympathetic" and "stern") which express contrasting attributes about the two persons. The answer to the first and the second sentence must be PersonX and PersonY, respectively. PersonX and PersonY should not be equally likely to fill the blank. For each sentence, there should be an agreed upon answer to fill in the blank. Your generations should NOT contain potentially explicit, offensive, or adult content. Do not use the names of real people (e.g., Donald Trump, Putin, etc.) in your sentences. Avoid repeating the same style or phrase in twin sentences e.g., a contrasting sentence can always be created using simple negation i.e. by adding not, never, etc. Instead, try to increase diversity. Both twin sentences must contain at least 15 and at most 30 words. Twin sentences must have at least 70% overlapping words. You must utilize the given context word while writing the twin sentences. Each of the twin sentences must contain only one blank. Make sure that PersonX and PersonY have the same gender. In each sentence, PersonX and PersonY should be used only ONCE and PersonX should appear earlier than PersonY.

Context Word: immune system.
Sentence 1: PersonX had a strict regimen of taking supplements but PersonY didn't take any. _ had a strong immune system. 
Sentence 2: PersonX had a strict regimen of taking supplements but PersonY didn't take any. _ had a weak immune system.

Context Word: penny.
Sentence 1: PersonX only bought a few pieces of penny candy and PersonY got a big bag full, because _ 's parents could afford a meager allowance. 
Sentence 2: PersonX only bought a few pieces of penny candy and  PersonY got a big bag full, because _ 's parents could afford a generous allowance.

Context Word: freshwater.

Sentence 1: PersonX introduced PersonY to the sport of freshwater fishing, because _ grew up right next to a lake. 
Sentence 2: PersonX introduced PersonY to the sport of freshwater fishing, although _ grew up right next to a lake.