Indicating whether the following statements are true (t) or false (f).

1. the difference of two rational numbers is always a natural number.

2. the ratio of two rational numbers is always positive

3. the difference of two rational numbers is always a rational number.

4. the quotient of two rational numbers is always a real number (provided the denominator is non-zero).

5. the quotient of two rational numbers is always a rational number (provided the denominator is non-zero).

6. the sum of two rational numbers is always a rational number.

7. the product of two rational