I cant figure this word out it is missing the 2nd 4th and 6th letter

R F E IVO

2nd:  E

4th:   L

6th:  X

Explanation:

R E F L E X I V O

REFLEXIVO.

when the outside temperature is too cold, an endothermic animal can generate heat by shivering. endothermic animals must eat much more often than ectothermic animals since it takes energy to maintain a constant body temperature.

answerestan corriendo; i believe this is correct, plz check first good luck;