有关Na2CO3和NaHCO3的叙述中正确的是 A区别NaHCO3与Na2CO3

________,  I believe, and you will find Tom is very outgoing. [ ] 

A. Having a talk with the student

B. One talk with the student

C. Given a talk with the student

D. If you have a talk with the student

冲击地压是发生在（）过程中的动力现象。

有两只相同的大桶和一只空杯子，甲桶装牛奶，乙桶装糖水，先从甲桶内取出一杯牛奶倒入乙桶，再从乙桶取出一杯糖水和牛奶的混合液倒入甲桶，请问，此时甲桶内的糖水多还是乙桶内的牛奶多？（）

A.无法判定

B.甲桶糖水多

C.乙桶牛奶多

D.一样多

排牙实验锯开模型时，应从（）

A．牙颈缘线4～5mm处的连线锯开

B．牙颈缘线3～4mm处的连线锯开

C．牙颈缘线5～6mm处的连线锯开

D．牙颈缘线2～3mm处的连线锯开

E．牙颈缘线1～2mm处的连线锯开