第二部分：词汇知识运用（共两节，满分30分）
第一节：单项选择（共10小题；每小题1分，满分10分）
从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
21. A new case study says Chinese companies face tough __________ in the US and have a long way to go to be successful.
A. challenges B. campaigns C. motivations D. dilemmas
22. A professor said the rise of the BRICS countries（金砖国家） is a/an __________ of the end of the world in the control of the USA.
A. barrier B. process C. aspect D. symptom
23. The new law of consumer rights also __________ rules about returning faulty goods and sets out protections
