心绞痛发作时疼痛的部位主要在
A．心尖部
B．胸骨后或心前区
C．咽、下颌部
D．剑突下
E．背部
参考答案：B
That guy appears to be an expert in this field of work. ____, he knows nothing about it. [ ]
A. So far
B. As a matter of fact
C. In other words
D. At all
板带钢生产中，影响厚度波动的因素有哪些？
