Section 4: Vocabulary and Structure (20%) 四.词汇与结构(20分) Directions: There are 10 incomplete sentences in this section. For each sentence there are four choices marked A, B, C and D. Choose the ONE answer that best completes the sentence. 答题要求:这一部分有十句不完整的句子,请从每题中所给的A、B、C及D四个选项中选出最佳答案使句子完整。 1. Please remember that it is ______ to interrupt people when they are speaking.