After two hours they stopped ____a rest. [ ]
A. having
B. have
C. to have
D. had
答案:C
所谓实质性加工,是指产品经加工后,在海关进出口税则中4位数一级的税则归类已经改变,或者加工增值部分占新产品总值的比例已达到30%及其以上。( )