工艺流程中加注甲醇的主要作用是（）。
A.防止硫沉积
B.抑制水合物生成
C.减缓管材腐蚀速率
D.提高天然气温度
参考答案：B
— Why is your father in such a hurry?
— He _____ for Beijing to attend an important meeting. The plan _____ at six. [ ]
A. will leave; leave
B. is leaving; leaves
C. is leaving; will leave
D. leaves; is leaving
A．核外电子数
B．核电荷数
C．中子数
D．质子数和中子数
