"They had felt the temperature."
Translation:Elas sentiram a temperatura.
I believe this is an example of a sentence having been translated from Portuguese to English in an odd, but correct way, and the odd translation accepted into the pool. What we are seeing here is the odd translation set as an exercise.
My guess is that the original meaning of "Eles sentiram a temperatura" was "They felt the temperature" (or possibly "They have felt the temperature") but someone pointed out that "sentiram" is also the "pretérito mais-que-perfeito" or synthetic pluperfect tense and asked for "They had felt the temperature" to be accepted. As I understand it the synthetic pluperfect is not used very often so "Eles sentiram a temperatura" is not going to be a popular answer. From what Paulenrique says the best way to translate this sentence is "Eles tinham sentido a temperatura". Is that accepted?
They had felt the temperature = Eles (Elas) tinham sentido a temperatura / They have felt the temperature = Eles (Elas) sentiram a temperatura.
When you have "had+participle", translate had as "tinha, tínhamos, tinham"