Question

heart rate know - how
an average healthy adult has about two of blood, and it
takes approximately 60 for the cycle to be completed.

Explanation:

These are standard physiological facts about human blood volume and circulatory cycle time. The typical blood volume for a healthy adult is often cited in gallons (around 1.5-2 gallons, matching the blank), and the full circulation of blood takes roughly 60 seconds (1 minute) to complete.

Answer:

1. gallons
2. seconds