齿轮传动的优缺点

请问在看流星雨时能听见个别流星有声音这是正常的物理现象吗?深夜,在看狮子座流星雨时,我看到一颗流星划过,伴随着像是在指甲上弹硬币的声音.很清脆的“嘣”的一声.请问流星雨发声的 流星流过的声音是什么声音.就几下即可.哪来做手机短信铃声.就是那首“不要在我寂寞的时候说爱我”这首歌,刚开始1、2秒时候的音乐声音.就是想流星之类的声音吧.是什么声啊.在哪里有只 有首英文歌高潮好像是“every sa la la la every one”是什么歌? 百米赛跑时,终点计时员听到发令枪声才开始计时,所记录运动员成绩为13.69秒,该运动员真实成绩为多少 英语连词成句 to,what,you,drink,do,want 英语智力题：what table is in the field? 急求好听的英文歌曲,重音、男女声、伤感、快节奏等都可以,好听就行.如果好听我会加分!可以参考问题说明可以是男声(如that's why you go away之类) 也可女声(如moonlight shadow之类) 也可是中文翻 英lie的lie怎么写 Where were you yesterday?-I stayed home,reading books.A.at B.in C.for D.she You were at home last Saturday ,__ ____(反义疑问句） 人教版初二上物理第一章：在百米赛跑,站在终点的计时员如果在听到枪声才计时,他记录下来成绩误差有多大 百米赛跑时,计时员听到枪声后开始计时,他记录下的成绩准确吗?为什么?应该怎样做才能减小误差急用 圣诞节班会英语主持稿（速度）!我很快就要用,一定要是两个人的,有中文翻译,篇幅正常,词汇不要太拗口，稍微易懂一点，但不要太弱智，有点幽默感，能显出水平。并且不要是歌曲，一定 你认为我国当前经济发展存在哪些机遇? 运动会上进行百米赛跑时,终点裁判员看到（ ）记时,若听到枪声再记时, I tried to _________ you at home several times,but no one answered the phone.A．touch B．reach C．receive D．meet I Tried to -----you at home several times ,but no one answered the phone . I was traveling around last month A.touch B.reach C.receive D.meet 为什么 I tried to ___ you many times,but no one answered the phone.(用什么?touch,reach,receive,meet) I tried to ____you at home,but you didn't answer the phone--I was traveling around last monthA.touch B.reach C.meet我们老师说 这个题选B tried to phone you several times to tell you the news,but I couldn't____.A、get through B、get along C、go through.D、get to cousin和house中的ou发音相同吗 house的ou和forest的or发音相同吗 house mouth soup的ou发音一样吗 (1-1/2)*(1/2-1/3)*(1/3-1/4)*(1/4-1/5)*(1/5-1/6)怎么做 2.3.4.5.6.7怎么做 I’ll give you my friend’s home address,__I can be reached most evenings 填where那个被动语态解释下,reach不是及物动词吗 为什么不用which Where have you been _____ you left home?A.before B.as C.since D.when 一想一念后各跟一人,一分一秒后物是人非,爱与情尽只空余此恨,破若留恋何以弃之不顾,温柔乡里何为肺腑言,心碎到头向人伴身旁,曾经低三下四求回头,问汝心中可曾忘却过,侧于汝身之下海 孔子是哪个朝代的思想家,教育家?他有什么重要贡献? 新版新概念英语第二册第49课练习册答案, A:What did you do after school last Monday?B:I__the__at home 是6AU5的 Where ___ you last SaturdayA.did B.are C.were