试叙述静电起电序列产生的依据或方法，为何摩擦序列会产生波动？简述减少和防止静电的方法

一般天然气的爆炸极限为（）。

A、1%—5%

B、4%—15%

C、6%—26%

D、8%—26%

添加防腐剂保存食品是最好的现代食物保存方法。[ ]

Have fun with stamp collecting．．．Join   Collectors Club Starter Pack

the Collectors Club today!        1.100 used stamps and hinges

If you enjoy learning all about stamps，then    2.The Collectors Club Guide to Collecting

the Royal Mail’s Collectors Club is for you．   3.The latest Collectors Club magazine

Join the club and discover the fascinating        (packed with news and views about

world of stamps．There are over 70,000           stamps，quizzes and competitions，all in

members and it is one of the biggest clubs of          color)

its kind in the country．              4．Album pages

Become a member today and you will receive   5．Badge and stickers

lots of wonderful stamp collecting goodies．．．      6．Membership card

·A Starter pack…               7．Royal Mail Stamp Calendar

And every two months．．．                      * * * * * * * * * * * * * * * * * * *

·Collectors Club magazine        Already Registered?

·Collectors Corner supplement         Sign In Here!

And every year．．．             Learn More

·A new Stamp Calendar      View a Flash Presentation

·A set of Album Pages        about our club(3．51MB)

Join today!               Crick here：

It won’t cost you much to experience the fun     http：//www．Collectors Club/introduction swf

of stamp collecting．

60．This advertisement is written for people who want to        ·

A．find out where the club is                B. get something free from the club

C．develop stamp collection as a hobby        D．make money through collecting stamps

61.  From the advertisement we can learn       ．

A．Collectors Club is among the biggest clubs of its kind in the country

B．how much you must pay to become a member of the club

C．today is the last day for stamp collectors to join the club

D．members may receive a set of album pages every month

62．Where is this advertisement most probably found?

A．In a newspaper．       B．On a web page．

C．In a magazine．           D．On a TV program． 

新生儿早期下述哪一种细胞的功能未降低（）

A.TH2细胞

B.中性粒细胞

C.巨噬细胞

D.B淋巴细胞

E.树突状细胞

女性，21岁，高热伴牙龈肿痛1周，应用抗生素治疗无效。胸骨压痛明显，浅表淋巴结及肝脾不大。WBC3．8×10⁹／L，HCB54g／L，PI．T20×10⁹／L。肝功：LHD2500U/L。骨髓检查：原始细胞增多≥85％，POX阴性，PAS阴性，非特异性酯酶（+），能被NaF抑制，NAP正常

本例的诊断是（）

A.急性粒细胞白血病

B.急性早幼粒细胞白血病

C.急性单核细胞白血病

D.急性淋巴细胞白血病

E.急性红白血病