现有下列数据，用对应的序号填空
A．45° B．90° C．
D．2 3
E．1 3
F．0.1g G．0.01g1 4
①在初中化学实验中所用的托盘天平一般准确称量到______；
②向酒精灯里添加酒精，不可超过酒精灯容积的______；
③给试管里的液体加热时，应使用试管夹，夹在离试管口约______处，试管里液体体积不超过试管容积的______，试管要与桌面成的______角，试管口不要对着自己或旁人．
①天平的准确度为0.1g，所以天平在读数时，读数要保留小数点后的一位．
②酒精灯内的酒精的量不能超过酒精灯容积的2/3，也不能少于1/3．
③给试管里的液体加热时，液体不能多于试管容积的1/3，若过多，在加热时，液体会飞溅．试管夹应夹在试管的中上部，且试管与桌面成45°．
故答案为：
①F
②C
③D；D；A．
Third-generation mobile phones, known as 3G, are the next big step for the telecom industry. Data speed in 3G networks is much quicker than that in present technology. This means users can have high-speed Internet access and enjoy video and CD-quality music on their phones.
"Mobile data is not a dream; it’s not an option but a requirement," said Len Lauer, head of a US communications company, Sprint PCS, at a 3G conference in Bangkok earlier this month.
With 3G, you can forget about text messages telling you yesterday’s news; a 3G phone can receive video news programs, updated four times a day. Internet access will also be much quicker, making it easier to surf the Web on your phone than on your computer at home.
Don’t worry about getting lost. 3G phones offer map services so you can find a new restaurant just by pressing a few keys on your handset.
However, the most impressive part of 3G technology is video calling. With live two-way video communication, you can have face-to-face talks with friends and family on your mobile phone.
Many European countries have already launched the service. In May 2000 the US Government issued five license to run 3G wireless services, while the first 3G phones arrived in Italy in March this year.
International telecom companies can’t wait to sell 3G in China, the world’s largest mobile telecommunications market. But they will have to be patient. At the moment, China is busy testing its 3G-based technologies, networks and services. This will be followed by a trial period before the phones can finally hit the shops.
"We need to create a pool of 3G customers before the large-scale commercial launch of the service," said Fan Yunjun, marketing manager for Beijing Mobile. "We expect that the 3G licenses will be issued late next year.
| Third-generation mobile phones (3G mobile phones) | |
| (1) |
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| Impressive functions | a. Offer (6) services, helping you find your wayb. Provide two-way video (7) |
| 3G phones in China | a. China is busy (8) its 3G-based technologies, networks and services.b. 3G phones should go through a (9) period before being put into market.c. 3G phones are expected to be seen (10) next year. |
第（7）空应填（）