Ответ:

Объяснение:

1) Pavlov died at the age of 86.

2)  b. Cannon has been written by Avicenna.

3) Третье, это ответы на второе.

4) d. It is estimated that the weight of the brain is about two kg.

5) b. was treating.

6) c. have to.

7) b. should.