体外人工心脏按压的频率最好掌握在每分钟（），但不能低于每分钟（）。
参考答案：70--80次；60次
可止血又可用于血虚心烦失眠、虚劳咳喘的药物是
A．玉竹B．黄精C．百合D．阿胶E．龙眼肉
In relation to the Labour Law of China:
(b) Describe the conditions under which an employee and the employer may terminate a labour contract during the period of probation respectively. (4 marks)
