某路由器(在图17-16中没有标出)的部分配置信息如下所示，请解释其中标有下划线部分的含义。
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!
username sp_lac password 7 104D00 0A0618
username Bob password 7 06050 6324F41
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vpdn enable 第 (3) 处
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vpdn-group 1 第 (4) 处
accept dialin 12tp virtul-template 1 remote sp_lac 第 (5) 处
local name Bob 第 (6) 处
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lcp renegotiation always 第 (7) 处
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no 12tp tunnel authentication 第 (8) 处
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参考答案：建立VPDN组，编号为1。
| 完形填空 | |||
| When the Americans were getting ready to send their first man to the moon,an old Irishman(爱尔兰人)was 1 them on TV in a hotel room.There was an Englishman in the room, 2 .And he said to the Irishman,"The Americans are very 3 , aren't they? They are going to send some people to the moon. It's a very 4 way from our world." "Oh, that's 5 ,"the Irishman answered quickly. "The Irishmen are going to send some people to the sun in months' 6 . That's much 7 away than the moon,you know. "The Englishman was very 8 when he heard this. "Oh,yes, it is," he said. "But the sun is too 9 for people to visit." The Irishman laughed and answered,"Well,the Irish are clever, too, you know. We 10 go to the sun during the day,of course. We'll go there during the night." | |||
| ( )1. A. reading ( )2. A. too ( )3. A. kind ( )4. A. short ( )5. A. nothing ( )6. A. later ( )7. A. far ( )8. A. angry ( )9. A. warm ( )10.A.don't | B.watching B.also B.bad B.long B.all B.ago B.never B.surprised B.big B.won't | C.making C.of course C.clever C.far C.wrong C.long ago C.farther C.glad C.cold C.want to | D.mending D.only D.good D.near D.great D.time D.longer D.sorry D.hot D.must |
开始加速运动，经时间t前进了s的距离，此时速度达到最大值
。设在此过程中汽车发动机的功率恒为P，汽车所受的阻力恒为f，则在此段时间内发动机所做的功可表示为（ ）
