4．
阅读短文，回答问题
"Please help me find the Rh AB negative blood(熊猫血) for my father!" Miss Huang from Wuhan asked for help on Changjiang Daily on July 21, 2019. Her father was over 70 and he was in a serious situation when she took him to a hospital. He needed an immediate operation(手术), or he could lose his life. However, there was no Rh AB negative blood for him. The doctors had to put off the operation.
"An old man with Rh AB negative blood is in great danger. We need such blood for his operation!" Shen Jian who works in the Wuhan Blood Center called out the volunteers in their public QQ groups. He checked their information on the computer and called them one by one. Yu Zhou was doing housework when he received Shen's call at nine o'clock at night. He went to the center and donated(捐) 400 ml of blood at once. Wang Bing was at work when he picked up the phone. As soon as he finished working, he went to donate 400 ml of blood as well. Xu Huijun donated 200 ml. Tan Peng and Lu Juanzhi also donated their blood in the closest blood center.
By July 22, the five volunteers donated 1,600 ml of Rh AB negative blood after passing examinations. The doctor had an operation on the old man soon.
Just three percent of people own(拥有) Rh AB negative blood. Wuhan Blood Center set up three QQ groups for volunteers in 2002. They give their blood regularly(定期地) and have helped people in trouble for years.
