化工单元操作是如何分类的？

多伊奇认为,对于学生的同伴关系和学习动机能够产生更为积极影响的目标奖励结构是()。

A．竞争目标结构

B．个人主义目标结构

C．合作目标结构

D．友谊目标结构

根据销售合同审核信用证，将信用证存在的问题以及如何修改填入表格中。
(1)销售合同

(5)装运期限：
TIME OF SHIPMENT: SHIPMENT TO BE EFFECTED BEFORE MAR.1,2009
(6)装运港：
PORT OF LOADING: SHANGHAI CHINA
(7)目的港：
PORT OF DESTINATION: OSAKA JAPAN
(8)分批装运：
PARTIAL SHIPMENTS: NOT ALLOWED
(9)转船：
TRANSSHIPMENT: NOT ALLOWED
(10)付款条件：
TERMS OF PAYMENT: THE BUYER SHALL OPEN THROUGH A BANK ACCEP-FABLE
TO THE SELLER AN IRREVOCABLE SIGHT LETTER OF CREDIT WHICH REMAINS VALID FOR NEGOTIATLON IN CHINA UNTIL THE 15TH DAY AFTER THE DATE OF SHIPMENT.
(11)保险：
INSURANCE: TO BE COVERED BY THE BUYER.
(12)REMARKS: 10% MORE OR LESS IN QUANTITY AND AMOUNT IS ALLOEED.
Confirmed by：
买方 后藤均一 卖方 何锦
THE BUYER THE SELLER
(2)信用证
SEQUENCE OF TOTAL*27 : 1/1
APPLICABLE RULES *40 : IRREVOCABLE
DOC. CREDIT NUMBER*20 : LC-429-393536
DATE OF ISSUE *31C : 081225
EXPIRY *31D : DATE 090316
PLACE IN THE COUNTRY OF THE APPLI.
CANT
APPLICANT*50 : NINGBO YIXIN IMP. ＆EXP. CO., LTD.
NO. 1005 ZHONGSHAN ROAD(E.1),
NINGBO CHINA
BENEFICIARY *59 : SHINORMAN CO., LTD.
ITC BUILDING 6TH FLOOR SUITE 602
1-8-4 CHOME ISOBE-DORI CHUO-KU
KOBE JAPAN
AMOUNT *32B : CURRENCY HKD AMOUNT 39600,00
MAX. CREDIT AMOUNT*39 : UP TO USD39600,00
AVAILABLE WITH/BY*41D : ANY BANK BY NEGOTIAION
DRAFTS AT... *42C : DRAFTS AT SIGHT FOR FULL INVOICE
VALUE
DRAWEE *42A :
* ASAHI BANK LTD. ＜FORMERLY THE
* KYOWA SAIYAMA BANK. LTD.＞
* TOKYO
PARTIAL SHIPMENTS*43P : ALLOWED
TRANSSHIPMENT *43T : ALLOWED
PORT OF LOADING/AIRPORT OF DEPARTURE*44E: DALIAN, CHINA
PORT OF DISCHARGE/AIRPORT OF DESTINATION *44F: KOBE, JAPAN
LATEST DATE OF SHIP. *44C : 090301
DESCRIPT. OF GOODS*45A :
(1)3000PCS OF APRON ART NO. 96837 @USD5,00
(2)4000PCS OF APRON ART NO. 96838 @USD6,00
PRICE TERM：CIF KOBE
DOCUMENTS REQUIRED*46A :
+3/3 SET OF ORIGINAL CLEAN ON BOARD OCEAN BILLS OF LADING MADE OUT TO ORDER OF SHIPPER AND BLANK ENDORSED. MARKED "FREIGHT PREPAID" AND NOTIFY APPLICANT
+ORIGINAL SIGNED COMMERCIAL INVOICE IN 5 FOLD INDICATING CONTRACT NO.
+CERTIFICATE OF ORICIN IN 1 ORIGINAL AND 1 COPY.
+PACKING LIST IN 3 FOLD
+WEIGHT LIST IN 3 FOLD
ADDITIONAL COND.*47 :
1．T.T. REIMBURSEMENT IS PROHIBITED.
2．10PCT MORE OR LESS IN QUANTITY ACCEPTABLE.
DETAILS OF CHARGES *71B : ALL BANKINC CHARGES OUTSIDE JAPAN INCLUDING REIMBURSEMENT COMMISSIONS ARE FOR ACCOUNT OF BENEFICIARY.
PRESENTATION PERIOD *48 : DOCUMENTS TO BE PRESENTED WITHIN 5 DAY AFTER THE DATE OF SHIPMENT, BUT WITHIN THE VALIDITY OF THECREDIT.
CONFIRMATION *49 : WITHOUT
INSTRUCTIONS *78:
THE NEGOTIATION BANK MUST FORWARD THE DRAFTS AND ALL DOCUMENTS BY REGISTERED AIRMAIL DIRECT TO US (INT’L OPERATIONS CENTER MAIL ADDRESS:C.P.O.BOX NO.800 TOKYO 100-91 JAPAN) IN TWO CONSECUTIVE LOTS, UPON RECEIPTOF THE DRAFTS AND DOCUMENTS IN ORDER, WE WILL REIMBURSE THE NEGOTIATINGBANK IN ACCORDANCE WITH THEIR INSTRUCTIONS.

功能性矫治器每天最少戴用时间为（）。

A.4～5小时

B.24小时

C.10～12小时

D.18小时

E.8～10小时

办理柜面通业务需遵循（）业务操作流程。

A.持卡办理查询卡内余额

B.无卡办理查询卡内余额

C.持卡办理存取款业务

D.无卡办理存取款业务

[背景材料]
某市煤气公司液化气站一个400m³液化石油气球罐发生破裂，大量液化石油气泄漏，顺风向北扩散，遇明火发生燃烧，引起球罐爆炸。大火连续燃烧将近20小时，致使该液化气站的多个球罐和油气瓶(其中空瓶3000多只)爆炸或烧毁，罐区相邻的厂房、建筑物、机动车及设备等被烧毁或受到不同程度的损坏，直接经济损失约800万元，死亡40多人，重伤50多人。后经有关部门调查研究发现，该球罐自投用后，一直没有进行过检查，破裂前，安全阀正常，排污阀正常关闭。可能导致破裂的原因大致如下：
(1)根据断口特征和断裂力学的估算，该球罐的破裂是属于低应力的脆性断裂，主断裂源在上环焊缝的内壁焊趾上，长约65mm。
(2)球罐焊缝表面及内部存在很多咬边、错边、裂纹，熔合不良、夹渣及气孔等缺陷。
(3)发生事故前在上下环焊缝内壁焊趾的一些部位已存在纵向裂纹，这些裂纹与焊接缺陷(如咬边)有关。
(4)球罐自投入使用后，从未进行检验，制造、安装中的先天性缺陷未及时发现和消除，使裂纹扩展。
根据以上场景，回答下列问题：

做好压力容器的维护保养工作，可以使容器经常保持完好状态，提高工作效率，延长容器使用寿命。容器的维护保养工作有哪些