列哪种保藏技术是经过降低食品的水分活性来达到防止食品腐败变质的（）
A．腌渍保藏
B．烟熏保藏
C．辐照保藏
D．高压保藏
参考答案：A
治疗霍乱的关键措施是（）
A.抗菌治疗
B.血管活性药物的应用
C.补充血容量及电解质
D.强心药物的应用
E.抑制肠黏膜分泌药的应用
About 80 percent of the students in our school_____ been working on the program and about two-thirds of the work _____been finished.
A．have; has
B．has; have,
C．have; have
D．has; has
