một cậu bé đi lên núi với vận tốc 1m/s. khi còn cách đỉnh núi 100m cậu bé thả một con chó và nó bắt đầu chạy đi chạy lại giữa đỉnh núi và cậu bé. con chó chạy lên đỉnh núi với vận tốc 2m/s và chạy lại phía cậu bé với vận tốc 4m/s. tính tổng thời gian những lần chó chạy lên (kể từ khi thả chó cho đến khi cậu bé và chó cùng gặp nhau trên đỉnh núi).
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All of them have ready to give a book report. -> All of them are ready to give a book report. We are much interested in English. -> We are very much interested in English. Ask when he made the cake. -> Ask him when he made the cake. Jane has never seen an elephant before. -> Jane has never seen an elephant before. Enjoy books in spare time. -> I enjoy reading books in my spare time. Hok tốt
Dưới đây là các câu hoàn chỉnh với các từ đã cho:
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All of them have ready to give a book report. -> All of them are ready to give a book report.
-
We are much interested in English. -> We are very much interested in English.
-
Ask when he made the cake. -> Ask him when he made the cake.
-
Jane has never seen an elephant before. -> Jane has never seen an elephant before.
-
Enjoy books in spare time. -> I enjoy reading books in my spare time.
/s/: stops, arts, laughs, rocks
/iz/: quizzes, fixes, watches
/z/: friends, prefers
1. To learn the regulations is difficult
=> it is...difficult to learn the regulations.
2. To pratise swimming is good for your health
=> it is good for your health to practice swimming.
3. To help him write his name on the board was necessary
=> it was...necessary to help him write his name on the board.
4. To get acquainted with newcomers is easy
=> it is not... difficult to get acquainted with newcomers.
1. To learn the regulations is difficult
=> it is...difficult to learn the regulations
2. To pratise swimming is good for your health
=> it is good for your health to practise swimming
3. To help him write his name on the board was necessary
=> it was...necessary to help him write his name on the board
4. To get acquainted with newcomers is easy
=> it is not... difficult to get acquainted with newcomers
1. Do you agree .with.. me .on..this problem?
2. Making friends is easy .for.. him
3. Let's listen ..to. what he says
4. I cannot help you now because i am ..in. a hurry
5. What are you afraid .of..?
6. The street is crowded .with.. people
7. He was born .on.. June 15th , 1987
8. I intend to buy something .for.. my mother
9. Tom often takes a bus .to.. his school
\(n_{co_2}=\dfrac{0,896}{22,4}=0,02\left(mol\right)\)
\(n_{BaCl_2}=\dfrac{100.20,8\%}{208}=0,1\left(mol\right)\)
PTHH :
\(BaCl_2+Na_2CO_3\rightarrow BaCO_3+2NaCl\) (1)
Như vậy : dung dịch X gồm \(BaCO_3;NaCl;\) có thể có \(BaCl_2\) dư hoặc \(Na_2CO_3\) dư
PTHH :
\(BaCO_3+H_2SO_4\rightarrow BaSO_4+CO_2+H_2O\) (2)
ctc : \(Na_2CO_3+H_2SO_4\rightarrow Na_2SO_4+CO_2+H_2O\) (3)
+) TH1 : Nếu \(BaCl_2\) dư ( không có phản ứng (3) )
Theo phương trình (2) \(\Rightarrow n_{BaCO_3}=n_{CO_2}=0,04\left(mol\right)\)
Theo phương trình (1) \(\Rightarrow n_{Na_2CO_3}=n_{BaCO_3}=0,04\left(mol\right)\)
\(\Rightarrow m_{Na_2CO_3}=0,04.106=4,24\left(g\right)\)
\(\Rightarrow C_{\%ddNa_2CO_3}=\dfrac{4,24.100\%}{100}=4,24\%\)
BTKL \(\Rightarrow m_{ddBaCl_2}+m_{ddNa_2CO_3}+m_{ddH_2SO_4}=m_{ddspứ}+m_{CO_2}\)
\(\Rightarrow m_{ddBaCl_2}+m_{ddNa_2CO_3}+m_{ddH_2SO_4}-m_{CO_2}=m_{ddspứ}\)
\(\Rightarrow m_{ddspứ}=100+100+100-0,04.44=298,14\left(g\right)\)
+) TH2 : Nếu \(Na_2CO_3\) dư ( xảy ra phản ứng (3) )
Theo phương trình (1) \(\Rightarrow n_{BaCO_3}=n_{BaCl_2}=0,1\left(mol\right)\)
Theo phương trình (2) \(\Rightarrow n_{CO_2\left(2\right)}=n_{BaCO_3\left(1\right)}=0,1\left(mol\right)>0,04\left(mol\right)\) ( vô lí )
\(\Rightarrow\) TH2 loại
1. What are you fond ..of.
2.The schoolboys and schoolgirls gathered .in.. small groups and talked .to.. one another
3. It is difficcult to get acquainted ..with. newcomers
4. My from teacher is rather strict ..with. us
5. They look at their new school .with.. curious eyes
6. The pupils were busy ..with. their work
Sửa đề: Kẻ đường thẳng vuông góc với NP tại P và đường thẳng vuông góc với MQ tại Q, hai đường thẳng này cắt nhau tại E
Gọi K là giao điểm của MQ và NP
Xét ΔKQE vuông tại Q và ΔKPE vuông tại P có
KE chung
EQ=EP
Do đó: ΔKQE=ΔKPE
=>KQ=KP
=>ΔKQP cân tại K
=>\(\hat{KQP}=\hat{KPQ}\)
=>\(\hat{MQP}=\hat{NPQ}\)
Hình thang MNPQ có \(\hat{MQP}=\hat{NPQ}\)
nên MNPQ là hình thang cân
1 She arrived in Hanoi on Monday morning.
2 My father used to take me to the zoo when I was a child.
3 She is busy with her housework now.
4 Her performance made a deep impression on the audience.
5 Tom is very friendly with his classmates.
6 I saw you walking past the mosque on the way to my school.