Analysis of test questions: The blood volume of adults is about 7-8% of body weight. Normal blood volume is the basis of normal metabolic activities of human body, with blood loss exceeding 30%, that is, exceeding 1200 ~ 1500 ml. Because the blood volume is not enough to maintain normal blood volume and blood pressure, it will be life-threatening, and the blood loss will not exceed 10%, which is 400 ml. It will also be replenished in a short time and return to normal. Water and inorganic salts can return to normal in 2 hours, plasma protein concentration can return to normal in about 1 day, and red blood cells 1 month (about two weeks). It can be seen that D meets the meaning of the question.
Comments: This question is a basic one. You should memorize the basic knowledge of human blood volume, blood loss and the amount of blood donated by healthy adults each time.