单项选择题
In this section, you will hear one passage. At the end of the passage, you will hear four questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A), B), C) and D).A、Bricks. B、A mixture of rock and soil. C、Concrete. D、Steel.
单项选择题 药品质量标准的主要内容（ ）A. 名称、性状、正文、规格与用途B. 结构、正文、贮藏、制剂与用量C. 鉴别、检查、含量测定、记录与报告D. 鉴别、检查、含量测定、稳定性试验E. 性状、鉴别、检查、含量测定
单项选择题 Which of the following words doesn't have fricative? A. shirt B. bad C. without
单项选择题 设随机变量X与Y相互独立且同分布，记U=X-Y，V=X+Y,则随机变量U与V（ ）．
