单项选择题
They do this by doing well-informed about their subjects, being honest in what they say, by using sound evidence, and by employing（）reasoning.
A.valley B.value C.vary D.valid
单项选择题 The interaction of these seven elements is what determines the（）in any instance of speech communication.
单项选择题 Interference is anything that（）the communication of a message.
单项选择题 Whatever the speaker communicates is the message, which is sent（）a particular channel.
