题目

The _______ Prime Minister expressed his satisfaction with his talks, _______ that he had enjoyed his stay here. A．visiting; add            B．visited; adding C．visiting; adding          D．visited; added 答案：C在盛有新鲜血液的试管中加入少量抗凝集剂（如：柠檬酸钠），静止一段时间后，上层呈淡黄色半透明的液体是 A．红细胞           B．血清             C．血小板           D．血浆