下列有关燃料的叙述错误的是（ ） A．氢气是最清洁的能源 B．酒精属于不可再生能

对于△ABC，有如下命题：

①若sin2A=sin2B，则△ABC 一定为等腰三角形；

②若sinA=sinB，则△ABC 一定为等腰三角形；

③若sin²A+sin²B+cos²C<1，则△ABC一定为钝角三角形；

④若tanA+tanB+tanC>0，则△ABC一定为锐角三角形。

其中正确的命题的有[ ]

A.①②③

B.①③④

C.②③④

D.①②④

阅读理解。

     Joanne was stuck in a traffic jam in central Birmingham at 5?30,and at 6?30 she was expected

to be chairing a meeting  of the tennis club. At last, the traffic was moving. She swung quickly

racing to her house. As she opened the door, she nearly tripped over Sheba.

    "Hey,Sheba," she said, "I've got no time for you now, but I'll take you out as soon as I get back

from the tennis club." Then she noticed Sheba seemed to be coughing or choking.  Obviously, she

could hardly breathe.  Immediately, Joanne realized she would have to take her to the vet (兽医)．

    When she got there, the vet was just about to close for the day. Seeing the state of Sheba, Dr.

Sterne brought her quickly into his office.

    "Listen, doctor, I'm really in a rush to get to a meeting, can I leave her with you,and go to get

changed? I'll be back in ten minutes to pick her up, and then I'll take her on to the meeting with

me. Is that OK?"

    "Sure." said the doctor.

    Joanne made the quick trip back to her house in a couple of minutes. As she was once more

entering the hallway, the phone by the door began to ring.

    "This is Dr. Sterne," said an anxious voice. "I want you to get out of that house immediately,"

said the doctor's voice. "I'm coming round to right away, and the police will be there any time

now. Wait outside!"

    At that moment, a police car screeched to a stop outside the house.  Two policemen got out

and ran into the house. Joanne was by now completely confused and very frightened. Then the

doctor arrived.

"Where's Sheba? Is she OK?" shouted Joanne.

"She's fine,Joanne. I took out the thing which was choking her,and she's OK now."

Just then, the two policemen reappeared from the house, carrying a whitefaced man, who could

hardly walk. There was blood all over him.

"My God," said Joanne, "how did he get in there? And how did you know he was there?"

"I think he must be a burglar." said the doctor. "I knew he was there because when I finally

removed what was stuck in Sheba's throat, it turned out to be three human fingers."

1. What was Joanne supposed to do at 6:30?

A. To walk her dog.

B. To see her doctor.

C. To attend a club meeting.

D. To play tennis with her friends.

2. Joanne wanted to get back to her home again ________.  

A. to dress up for the meeting

B. to phone the police station

C. to catch the badly hurt burglar

D. to wait for her dog to be cured

3. From the passage, we can infer that ________.

A. Sheba fought against the burglar

B. the police found the burglar had broken in

C. Joanne had planned to take her dog to the meeting

D. the doctor performed a difficult operation on the dog

4. In this passage, the writer intends to tell us that the dog is ________.

A. clever      

B. friendly  

C. frightening  

D. devoted

京华百货公司兼营批发、零售、服务等业务，按照楼层分设家电组、黄金珠宝组、服装组、化妆护肤组、图书音像组，在财务部分账核算，统一纳税。另将顶层承包给SSY饮食公司经营饮食大世界，饮食收入由SSY公司掌握，百货公司每月收取SSY承包费30000元。2009年6月发生如下业务：
(1)家电组采用交款提货方式零售彩电，取得现金收入80000元；以旧换新方式销售电冰箱，实际收到零售金额40000元(已扣除了2000元旧冰箱折价款)；当月从厂家进货家电，增值税发票注明增值税15300元，其中10%奖励给本企业先进员工；当期修理小家电修理费收取现金27846元。
(2)黄金珠宝组当月零售翡翠手镯，零售金额55000元；零售包金手镯，零售金额5000元；零售18K金镶宝石首饰，零售金额50000元；以旧换新销售24K足金首饰，实际收零售额70000元(已扣除了30000元的旧的金饰品的折价款)，当月采购换金珠宝增值税发票注明增值税23800元。
(3)服装组代销服装厂服装，将向顾客收取现金150000元，平价与服装厂结款，按照零售额的25%向厂家收取代销手续费，另一次性收取服装厂20000元的与销售量无关的上架宣传费。
(4)化妆品组进口高档化妆品一批，货值500000元，支付采购中介佣金8000元、空运及保险费用13560元，化妆品关税率25%，入境后自口岸至厂区运费3000元，取得国际国运代理发票。批发和零售或妆品，不含税收入1000000元，支付批发货物的运费10000元和装卸费1000元，取得相关发票。
(5)图书音像组零售图书音像制品收入240000元，将市场零售价50000元的一批图书捐赠受灾地区，当月采购图书取得增值税发票，注明进项税11000元。
假定上述相关需要认证的发票均经过认证，要求按顺序计算解答：

服装组当期增值税的应纳税额为( )元。

A．0

B．5448.72

C．8354.70

D．9038.56

全冠粘固后出现龈缘炎，其原因不可能是（）

A.轴壁突度不良

B.冠边缘过长

C.冠边缘不密合

D.龈沟内粘固剂残留

E.咬合早接触

尖晶石最常见的晶形是（）

A.菱形十二面体

B.八面体

C.立方体