交换下列二次积分的次序:

A . Fe ＞Ca ＞Al ＞Na ＞H B . Al ＞Ca ＞Fe ＞Na ＞H C . Al ＞Fe ＞Ca ＞Na ＞H D . Fe ＞Al ＞Ca ＞Na ＞H

A .https://assets.asklib.com/psource/2015102917011683633.jpg B .https://assets.asklib.com/psource/2015102917014467452.jpg C .https://assets.asklib.com/psource/2015102917032793192.jpg D .https://assets.asklib.com/psource/2015102917034437496.jpg

A .https://assets.asklib.com/psource/2015102908463839977.jpg B .https://assets.asklib.com/psource/2015102908465216566.jpg C .https://assets.asklib.com/psource/2015102908470733418.jpg D .https://assets.asklib.com/psource/201510290847219913.jpg

A . 搅拌能力； B . 运输距离； C . 灌筑速度； D . 洞内气温； E . 振捣方法； F . 搅拌站料场的购料情况； G . 生产工人数量。

A .https://assets.asklib.com/psource/2015102915210334288.jpg B .https://assets.asklib.com/psource/2015102915211626790.jpg C .https://assets.asklib.com/psource/2015102915213172096.jpg D .https://assets.asklib.com/psource/2015102915214446563.jpg

A .https://assets.asklib.com/psource/2015102817295118607.jpg f（rcosθrsinθ）rdrB .https://assets.asklib.com/psource/2015102817295678522.jpg f（rcosθ，rsinθ）rdrC .https://assets.asklib.com/psource/2015102817300014340.jpg f（rcosθrsinθ）rdrD .https://assets.asklib.com/psource/2015102817300527359.jpg f（rcosθ，rsinθ）rdr

A . 由内到外 B . 由远到近 C . 左右开弓 D . 由职务高的到职务低的

A . A、由近而远 B . B、由远而近 C . C、左右开弓，同时进行

A .https://assets.asklib.com/psource/2015102917174668011.jpg B .https://assets.asklib.com/psource/2015102917180844389.jpg C .https://assets.asklib.com/psource/2015102917183436761.jpg D .https://assets.asklib.com/psource/2015102917185022062.jpg

A . A、⑴⑵⑶ B . B、⑵⑴⑶ C . C、⑴⑶⑵ D . D、⑶⑵⑴

二次积分<img src='https://img2.soutiyun.com/shangxueba/ask/17676001-17679000/17676154/2015102917004746434.jpg' />交换积分次序后的二次积分是（）。 A．<img src='https://img2.soutiyun.com/shangxueba/ask/17676001-17679000/17676154/2015102917011683633.jpg' /> B．<img src='https://img2.soutiyun.com/shangxueba/ask/17676001-17679000/17676154/2015102917014467452.jpg' /> C．<img src='https://img2.soutiyun.com/shangxueba/ask/17676001-17679000/17676154/2015102917032793192.jpg' /> D．<img src='https://img2.soutiyun.com/shangxueba/ask/17676001-17679000/17676154/2015102917034437496.jpg' />

A．从左到右 B．从右到左 C．从上到下 D．从下到上

<img src='https://img2.soutiyun.com/ask/2021-01-10/97914323460899.png' />

将二重积分<img src='https://img2.soutiyun.com/ask/2021-01-19/979920905720396.png' />按两种次序化为累次积分，积分区域D分别给定如下： (1)D由曲线y=x³与直线y=1，x=-1所围成，如图7-21所示; (2)D由圆x²+y²≤4所围成，如图7-22所示; (3)D由直线y=2x，y=0及x=3所围成，如图7-23所示. <img src='https://img2.soutiyun.com/ask/2021-01-19/97992096192361.png' />

把二重积分<img src='https://img2.soutiyun.com/ask/2020-12-28/978029335533442.png' />在直角坐标系中分别以两种不同的次序化为累次积分,其中(σ)为 <img src='https://img2.soutiyun.com/ask/2020-12-28/978029405558447.png' />