少量毒物长期与人体接触，逐渐侵入人体，积蓄起来引起中毒，称为（）。
A、急性中毒
B、慢性中毒
C、亚急性中毒
D、小量中毒
参考答案：B
I received an invitation to dinner from my friend,and with my work________,I gladly accepted it. [ ]
A. was finished
B. finishing
C. having finished
D. finished
螺纹的三大要素为牙型、外径和（）。
A.牙型
B.外径
C.内径
D.螺距
