棉纤维长度、线密度、有害疵点和（）等性能指标与成纱条干均匀度有密切关系。
A.反射率
B.黄色深度
C.回潮率
D.短纤维率
参考答案：D
下列物质中存在氧分子的是（ ）
A．高锰酸钾
B．双氧水
C．二氧化碳
D．液态氧
PPP stands for Presentation，Practice and （）. In PPP method classes or sequences, the teacher presents the context and situation for the language, and both explains and demonstrates the meaning and form of the new language. The students then practice making sentences before going on to another stage in which they talk or write more freely.
