数学教材封面背景图片

I’m certain he wasn’t in the classroom.I saw him in the library.这个句子可以说he is not 用现在时吗可不可以说I’m certain he isnt in the classroom.我确定他现在不再教室里 I saw him in the library.我刚才看到他在 He can't be in the classroom,I saw him go home a minute ago 我想问一下问什么不能用mustn't而用can't? He be in the classroom ,because I saw him talking withour teacher in the office just now A.must B.isn't able to C.can't D.will NO one will remember when you are right,everything even your breathe is wrong when you 介绍一下有关when的语法……,when……主要是时态弄不太懂 投影法在现实生活中的应用 怎样把SolidWorks2010的默认投影法改成中国的视图投影方法把第三角投影改成第一角投影,把坐标轴换成z轴朝上,x轴朝外,y轴朝左,主视图在yoz面上我的问题好像不是工程图的绘制,是那个在绘零件 英语同义句转换：To my surprise,my exam result was bad=I ___ _____ at my bad exam result. it count 30% ------ the final exam.A.to B.for.为什么?count打掉了s. HE ( ) in the classroom just now.he ( )be there now为什么答案是WAS　HEARd　TO SING 　, may 而不是was heard sing ,must 矿体储量计算纵投影勘探线与投影面怎么交汇 用射影法求异面直线所成角的范围?我在参考书上看到的一种方法,即将一条直线投影到一平面上,使两直线共面,再求夹角,可是有几条这么做可以做到,有几条又不可以·······想问问高手原 钚的半衰期是多长时间? The room is so dirty that we can't clean it.（改为同义句The room is ( ) dirty ( ) clean. I don't think there is( ) water in the bottle?填some 还是any I don't think there is__(some)water in the cup.(说一下原因, 基督山伯爵怎么用法语怎么表示,那英语呢 英语翻译这是那段话：Au dernier commandement,toutes les voiles s'abaissèrent,et le navire s'avança d'une façon presque insensible,ne marchant plus que par l'impulsion donnée. 用 cleaned the room 提问 There are two pictures in the magazine.I think the s one is better.填上那个s开头的单词 There is a surprised silence in the classroom.是运用什么英语修辞手法? can you clean your room ,i have cleaned it had 行么、 hopeless behind the times? 右眼皮跳是什么意思 He was seen () in the reading room an hour ago.A.sit B.sitting C.sat D.to sit我们老师说选D.可为什么不是B He was seen sit in the reading room an hour ago是哪里错了 相对论中提到的 物体在运动中会变短 如题 相对论中说：对处于运动中的物体来说时间会变缓这句话应该怎么理解?对于月台来说,火车是运动的,对于火车来说,月台也是运动的.如果爱因斯坦说的是对的,难道月台和火车都会认为对方的 John t_____ China when he was young. There are many apples on the desk?快啊.,There are many apples on the desk?快啊.,速度给我转换成疑问句和否定句. 左右眼皮跳的含义 眼皮跳的真正含义 眼皮跳的真正含义是?