One of the most important features that distinguishes reading from listening is the nature

One of the most important features that distinguishes reading from listening is the nature of the audience. 【C1】______ the writer often does not know who will read what he writes, he must 【C2】______ to be as clear as possible. Time can be taken to plan the piece of writing so that it is eventually organized into some sort of 【C3】______ sequence of events or ideas. When we speak, however, we 【C4】______ have very little time to plan what we intend to say. 【C5】______ , we may begin speaking before we have 【C6】______ what to say. Our thoughts then tumble out (不由自主的进入) in anything 【C7】______ a logical sequence.

Since we are actually 【C8】______ our audience face to face we may omit some of the information we believe our audience shares. 【C9】______ the more familiar we are with our audience, the more information we are likely to leave out. In any 【C10】______ they can always stop and ask a question or ask for clarification if we have left out too much. A reader, however, cannot do this, but can at least attempt comprehension 【C11】______ his own speed; 【C12】______ is to say, he can stop and go backwards or forwards, 【C13】______ to a dictionary or just stop and rest. When we listen we may have to work hard to sort out the speaker"s 【C14】______ by referring backwards and forwards while the speaker continues. As the speaker struggles to organize his thoughts, he will use filler phrases to give him time to plan. 【C15】______ these fillers, he will still make mistakes and repeat what he has already said. His speech will be characterized 【C16】______ a limited range of grammatical patterns and vocabulary and the use of idioms to 【C17】______ some general meaning quickly. It should be clear, then, that the listener has to take an active 【C18】______ in the process by ignoring the speaker"s repetitions and mistakes, and by seeking out the main idea information through recall and prediction. To keep the process going smoothly he also has to 【C19】______ the speaker that he has understood 【C20】______ actually interrupting.

【C1】

A．However

B．Although

C．Since

D．Unless

请帮忙给出正确答案和分析，谢谢！