A. harmful solids B. harmful gases C. harmful liquids D. harmful chemicals 参考答案:D 答案解析:根据短文里的界定:空气污染就是:Air pollution is the presence in the atmosphere of harmful gases, liquids,or solids.
第19题:[判断题] Firms pursuing global standardization or transnational strategies tend to prefer joint-venture arrangements over wholly owned subsidiaries. A.正确 B.错误 参考答案:B