自由资本主义的基本经济特征是自由贸易和自由竞争的实现。
参考答案：对
—How long has the nationwide ban (禁止) on plastic bags been put into practice?
－_____ the beginning of June.[ ]
A. Behind
B. Since
C. Among
D. At
相对于数字电视，CMMB的技术特点是什么？
