《专利法》规定，发明专利权的期限为（）年，实用新型专利权和外观设计专利权的期限为（）年，均自（）起计算。
参考答案：20；10；申请日
People appreciate________with him because he has a good sense of humor.[ ]
A. to work
B. to have worked
C. working
D. having worked
脑栓塞最常见的病因是( )。
A．糖尿病 B．动脉粥样硬化 C．风湿性心瓣膜病 D．高血压和动脉粥样硬化E．高脂血症
