井一防爆型的通信、信号和控制等装置，应优先采用（）型。
A、隔爆
B、本质安全
C、防爆特殊
参考答案：B
人在吸气时，下列哪一项与空气进入肺内无关（ ）
A．膈肌舒张
B．肋间外肌收缩
C．肺内压力降低
D．胸廓容积增大
You are a salesman in a pharmacy company. Write a letter to Mr. Wang, one of your customers, to introduce a new medicine to him.
Do not sign your own name at the end of the letter. Use "Li Ming" instead.
Do not write the address.
