安全监测设备（）至少调试、校正1次。
A.每年
B.每月
C.每季度
D.每周
参考答案：B
The settlement is home to nearly 1,000 people, many of（）left their village homes for a better life in the city.
A. whom
B. them
C. which
D. those
使胰蛋白酶原活化的物质主要是
A．盐酸
B．HC03ˉ
C．胰蛋白酶
D．糜蛋白酶自身
E．肠激酶
