优质解答
(1)P,Q,R,S四个人去公园玩跷跷板,已知S体重大于P体重,P与R的体重和大于Q与S的体重,Q与R的体重等于P与S的体重.请判断出这四人体重的大小关系.
∵S>P……①,P+R>Q+S……②,Q+R=P+S……③,
∴②-③,get:P-Q>Q-P
So:P>Q ……④
∵③&④,
∴R>S
∵①&②,
∴S>P>Q
∴R>S>P>Q.
(2)Which units are used to measure a horse?
a)metres b)hands c)legs d)litres
a
(3)His Chinese teacher is 30 years old at l____.
least
(4)What word is the first word on page 10 in your English-Chinese dictionary?
English word./Ten.(These answers are [uncertain].)
(5)I can stand still and go at the same time.What am
A clock.
(6)I am small,light and can move quickly.I can speak,though I have no mouth.I travel without feet,and Ican express my master's thiughts.What am I
Sound.
(7)The little traveller has great power.He takes a drink of water,and runs a thousand miles.Before he goes,he takes off his hat.When he rests,he puts on his hat.What is he?
[uncertain]
(8)Thank you very much for c_____ for our team.
cheering
(9)Her parents died in the accident,but she s____.
survived
(10)For people,these young men join the army without thinking about their own s_____ and d____.
safety,danger.
(11)this kind of i____ can make noise.
insects
(12)The cats leave and the m_____ play.
mice
(13)His work is to make b_____ chairs.
broad
(14)I have forests with no trees.I have rivers with no water,and I have cities with no houses.I have mountains with no rocks.What am
A map.
(15)某烧杯装满水后总质量为350克,放入一合金块后,溢出一些水,这时总质量为500克,取出合金后,总质量为300克,求合金的密度?
m合金=500g-300g=200g
V合金=V排=m排/ρ水=(350g-300g)/1.0g·cm[-3]=50cm[3]
ρ合金=m合金/V合金=200g/50cm[3]=4g/cm[3]
（16）气压计在一幢大楼底层的示数是755毫米汞柱,在大楼顶上的示数是751毫米汞柱,这幢大楼有多高?若每层楼高是3米,则这幢大楼有几层?
[This answer is [uncertain].]
p1=p汞gh1=13.6×10[3]kg/m3·9.8N/kg·755mm=100626.4Pa
p2=p汞gh2=13.6×10[3]kg/m3·9.8N/kg·751mm=100093.28Pa
h=p/(ρ空气g)=(p1-p2)/(ρ空气g)=533.12Pa/(1.29kg/m3·9.8N/kg)≈42.17m
n=h/3m=42.17m/3m≈14 (floors)
（17）潜水艇在海中潜行时排水量为800吨,在海面航行时排水量为650吨,试问潜水艇在海面航行时水上部分的体积有多大?要充进多少体积的海水才能潜入海底?（海水的密度为1030千克/立方米）
[This answer is [uncertain].]
V=m/ρ海水=(800t-650t)/(1.03×10[3]kg/m3)≈145.6m[3]
(1)P,Q,R,S四个人去公园玩跷跷板,已知S体重大于P体重,P与R的体重和大于Q与S的体重,Q与R的体重等于P与S的体重.请判断出这四人体重的大小关系.
∵S>P……①,P+R>Q+S……②,Q+R=P+S……③,
∴②-③,get:P-Q>Q-P
So:P>Q ……④
∵③&④,
∴R>S
∵①&②,
∴S>P>Q
∴R>S>P>Q.
(2)Which units are used to measure a horse?
a)metres b)hands c)legs d)litres
a
(3)His Chinese teacher is 30 years old at l____.
least
(4)What word is the first word on page 10 in your English-Chinese dictionary?
English word./Ten.(These answers are [uncertain].)
(5)I can stand still and go at the same time.What am
A clock.
(6)I am small,light and can move quickly.I can speak,though I have no mouth.I travel without feet,and Ican express my master's thiughts.What am I
Sound.
(7)The little traveller has great power.He takes a drink of water,and runs a thousand miles.Before he goes,he takes off his hat.When he rests,he puts on his hat.What is he?
[uncertain]
(8)Thank you very much for c_____ for our team.
cheering
(9)Her parents died in the accident,but she s____.
survived
(10)For people,these young men join the army without thinking about their own s_____ and d____.
safety,danger.
(11)this kind of i____ can make noise.
insects
(12)The cats leave and the m_____ play.
mice
(13)His work is to make b_____ chairs.
broad
(14)I have forests with no trees.I have rivers with no water,and I have cities with no houses.I have mountains with no rocks.What am
A map.
(15)某烧杯装满水后总质量为350克,放入一合金块后,溢出一些水,这时总质量为500克,取出合金后,总质量为300克,求合金的密度?
m合金=500g-300g=200g
V合金=V排=m排/ρ水=(350g-300g)/1.0g·cm[-3]=50cm[3]
ρ合金=m合金/V合金=200g/50cm[3]=4g/cm[3]
（16）气压计在一幢大楼底层的示数是755毫米汞柱,在大楼顶上的示数是751毫米汞柱,这幢大楼有多高?若每层楼高是3米,则这幢大楼有几层?
[This answer is [uncertain].]
p1=p汞gh1=13.6×10[3]kg/m3·9.8N/kg·755mm=100626.4Pa
p2=p汞gh2=13.6×10[3]kg/m3·9.8N/kg·751mm=100093.28Pa
h=p/(ρ空气g)=(p1-p2)/(ρ空气g)=533.12Pa/(1.29kg/m3·9.8N/kg)≈42.17m
n=h/3m=42.17m/3m≈14 (floors)
（17）潜水艇在海中潜行时排水量为800吨,在海面航行时排水量为650吨,试问潜水艇在海面航行时水上部分的体积有多大?要充进多少体积的海水才能潜入海底?（海水的密度为1030千克/立方米）
[This answer is [uncertain].]
V=m/ρ海水=(800t-650t)/(1.03×10[3]kg/m3)≈145.6m[3]