压力表应有存水弯管，存水弯管用钢管时，其内径不应小于（）mm。
A、5
B、10
C、15
D、20
参考答案：B
In relation to contract law:
(a) Explain the provisions of the Civil Code in respect of the time of conclusion of an agreement to enter into a legally binding relationship. (4 marks)
属于真核细胞型微生物的是( )
A．细菌 B．放线菌C．螺旋体 D．真菌
