叙述一下你对生物技术食品的安全性，特别是转基因食品的安全性有何看法？

阅读理解。

     In the US and many other countries. Tipping (给小费) is a way of saying thank-you to someone for his

good service. Who do you tip? And how much? Below are some tips (提示) for travelers in the US.

     1. Taxi drivers: $2 to $3; you give more if he helps you with your bags.

     2. Porters (搬运工): A standard tip (标准的小费) for porters is $1 each bag; more if your suitcases are

         very heavy.

     3. Hotel bellboy (青年侍者): Again, $1 for each bag. Tip him when he shows you to your room.

     4. Doorman (看门人): A $1 tip for calling a taxi. However, you may tip more for special service, such

         as shielding (挡住) you with an umbrella in the rain. You don't have to give the doorman anything just

         for opening the door or greeting you.

     5. Hotel maid (女佣): If you stay for more than one night, $1 each night is standard.

     6. Waiters and waitresses: 15-20% of your pre-tax (税前的) bill. In restaurants and bars in the US and

          Canada, 15% is the standard tip.

     7. Tour guides (导游): If a tip is not included in your bill, tip $1 for half-day tour, $2 for a one-day tour,

         and anywhere from $5 to $10 for a week-long tour.

     Now, it's sad to say that people have to give tips, even though the service is not good at all. So if you go

to the US, remember to carry a lot of change (零钱) for tips.

根据短文内容填空。

1. If a taxi driver helps you with your bag, you should pay for             $3 tips.

2. Tip the hotel bellboy             dollars if you have 3 bags to carry and you do not need him to show you

    to your room.

3. If a doorman             the door or              you, you needn't give the doorman anything.

4. You should give at least             dollars to the tour guide if you want a week-long tour.

5. You should give             dollars to a tour guide if you need a one-day tour.

风湿，脉浮身重，汗出恶风者，宜用的治疗方药是（）

A.桂枝附子汤

B.麻杏苡甘汤

C.麻黄加术汤

D.防己黄芪汤

E.白术附子汤

以下不属于直观判断法优点的是( )。

A．简单
B．快速
C．方便
D．科学

溴冷机中不凝气体存在会使机组（）。

A.产冷量下降

B.溶液易结晶

C.容易被腐蚀

D.无法正常运行

十二分钟跑可用来发展普通人的心肺功能。