土壤有机质的碳氮比在（），分解过程容易发生微生物与生物争夺氮现象 A.C/N B.C

如图（a）所示，长L=0.5m的轻杆AB，一端通过铰链固定于地面，另一端靠在固定于竖直墙壁上的压力传感器上．现将一质量m=0.2kg的小环套在轻杆上，t=0时刻从A处由静止释放小环，压力传感器的示数F_N随时间平方变化的F_N-t²图象如图（b）所示． 则在小环下滑过程的中间时刻，压力传感器承受的压力大小为______N，小环与轻杆间的动摩擦因数μ为______．（不计杆与压力传感器间的摩擦力）

阅读以下信用证，做选择填空。
(1)信用证内容
27: SEQUENCE OF TOTAL 1/1
40A: FORM OF DOCUMENTARY CREDIT IRREVOCABLE
20: DOCUMENTARY CREDIT NUMBER CRED1785669
31C: DATE OF ISSUE 090906
40E: APPLICABLE RULES UCP LATEST VERSION
31D: DATE AND PLACE OF EXPIRY 091102 U.S.A.
50: APPLICANT SILKROAD TEXTILES CO., LTD.
554E 8TH STREET A682
LOS ANGELES
U.S.A.
59: BENEFICIARY MEIYIJIA FABRIC CO., LTD.
150 RENMING ROAD
DALIAN 116002 CHINA
32B: CURRENCY CODE, AMOUNT: USD 76670
39A: PRECENTAGE CREDIT AMOUNT TOLERANCE 10/10
41A: AVAIIABLE WITH. BY. CITIU$33
42P: DEFERRED PAYMENT DETAILS AT 60 DAYS AFTER SIGHT C/O OUR COUNTERS
43P: PARTIAL SHIPMENTSNOT ALLOWED
43T: TRANSSHIPMENT NOT ALLOWED
44E: PORT OF LOADING/AIRPORT OF DEPARTURE DALIAN PORT, CHINA
44F: PORT OF DISCHARCE/AIRPORT OF DESTINATION LONG BEACH PORT, U.S.A.
44C: LATEST DATE OF SHIPMENT091017
45A: DESCRIPTION OF GOODS AND/OR SERVICES
+TRADE TERMS: CIF LONG BEACH PORT, U.S.A. ORIGIN: CHINA
+82000M of 100% POLYESTER WOVEN DYED FABRIC
AT USD 0.85 PER M
WIDTH: 150CM₁＞180CM₂
46A: DOCUMENTS REQUIRED
+SIGNED COMMERCIAL INVOICE THREE FOLD
+FULL SET OF CLEAN ON BOARD OCEAN BILL OF LADING MADE OUT TO THE ORDER AND BLANK ENDORSED, NOTIFY: APPLICANT(FULL ADDRESS)MARKEDFREIGHT PREPAID
+SIGNED DETAILED PACKING LIST
+CERTIFICATE OF ORIGIN
+HANDSIGNED INSURANCE POLICY/CERTIFICATE COVERING ALL RISKS AS PER I.C.C. FOR 110 PCT OF THE INVOICE AMOUNT
47A: ADDITIONAL CONDITION
10PCT MORE OR LESS IN AMOUNT AND QUANTITY ALLOWED
71B: CHARGES ALL CHARGES AND COMMISSIONS OUTSIDE U.S.A. ARE
FOR BENEFICIARY’S ACCOUNT
48: PERIOD FOR PRESENTATION WITHIN 15 DAYS
49: CONFIRMATION INSTRUCTIONS WITHOUT
78: INSTRUCTIONS TO THE PAYING/ACCEPTING/NEGOTIATING BANK AT MATURITY DATE, UPON RECEIPT OF COMPLYING DOCUMENTS C/O OURSELVES, WE WILLCOVER THE REMITTING BANK AS PER THEIR INSTRUCTIONS
(2)根据信用证内容回答下列问题：

信用证的受益人( )。

A．MEIYUIA FABRIC CO., LTＤ.

B．SILKROAD TEXTILES CO., LTＤ.

C．CITIUS33

汽机冲转前对DEH系统进行哪些检查和确认？

保险市场是保险商品买卖和交易相关行为的总和。

下列条件中与地球上存在生命物质有关的是（）

①适宜的太阳光照和温度范围

②地球的内部结构

③充足的水分

④恰到好处的大气厚度和大气成分

A.①②③

B.②③④

C.①③④

D.①②③④