起重机的钢绳上吊着一个重为G的物体，空气阻力不计，当物体停在_爱下问搜题

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问题选择题

起重机的钢绳上吊着一个重为G的物体，空气阻力不计，当物体停在空中时，钢绳的拉力是F₁；当物体以2m/s的速度匀速上升时，钢绳的拉力是F₂；当使物体以2m/s的速度匀速下降时，钢绳的拉力是F₃，那么下列关系式中正确的是 [ ]

A、F₁=G、F₂>G、F₃＜G

B、F₂>F₁>G、F₃＜G

C、F₁=F₂=F₃=G

D、F₁>G、F₂>G、F₃＜G

答案

答案：C

完形填空

完形填空。

     I'm in Madrid at the moment, visiting an old friend. It's a lovely city, but I'm having a few problems
with 1 !
     At home I usually have a small breakfast at seven thircy, then a sandwich  2 lunch at about one o'clock.
That's OK-it's about the game here. But I always  3 at about seven in the evening. Not here! In Madrid people
usually eat at about ten! In London I'm usually  4 by eleven, but here the streets are full every night until a long
time after midnight. My friend says a lot of people go to bed at two or three o'clock in the morning. I don't
understand. Everybody is up for work at seven or eight o'clock in the. morning. So when do they  5 ?

( )1. A. meals
( )2. A. for
( )3. A. have tea
( )4. A. get up
( )5. A. work

B. the eating times
B. at
B. have dinner
B. go to bed
B. have a meal

C. the working time
C. on
C. have a meeting
C. in bed
C. sleep

判断题

木材刨光消耗量：单面为1-1.5mm，双面刨光为2-3mm。