题目

句子翻译；将下列句子译成英语 1．我们都害怕在他人面前做演讲。 2．你得清楚地表达演讲的开头、要点和结尾。 3．你的演讲要够短才能引起他人的兴趣。 4．如果你的演讲不简单，就不会受到关注。 5．遵循这些建议，你就会成为杰出的演讲者。 答案：1. We are all afraid of making a speech in front of others. 2. You have to express the beginning, main points and the end of the speech clearly. 3.Your speech should be short enough to get / catch / attract others’ interest. 4. If your speech isn’t simple / easy, it will not be paid attention to. 5. Follow these suggestions and you will be an excellent speaker.已知数列{an}为等差数列，且a1＋a8＋a15＝π，a＝cos (a4＋a12)，则 xadx＝________.