mẹ : 6 phần

con:2 phần

theo sơ đồ ta có tổng phần bằng nhau

6 - 2 = 4 phan

tuổi mẹ  là

28 : 4 x 6 = 42 tuổi

tuổi con là

42 - 28 = 14 tuổi

Dễ thấy B,J,E thẳng hàng và C,K,E thẳng hàng
Gọi M là giao điểm AK với BC
Ta có 
Do đó tam giác ABM cân tại B
Mà BJ là tia phân giác nên cũng là đường cao nên BJ vuông góc AM
Tương tự CE vuông góc AJ
Tam giác AJK có JE và KE là đường cao nên AE cũng là đường cao hay AE vuông góc JK

1. There / about / twenty people / dancing club → There are about twenty people go to the dancing club

2. It / going / rain / we / should / close / doors → It is going to rain so we should close the doors

3. The Great Wall / interesting / than / Taj Mahal → The Great Wall is more interesting than Taj Mahal

4. Although / robots / expensive / they / very / useful → Althuough robots are expensive , they will be very useful
5. If / we / shower / instead / bath / we / save / water → If we take a shower instead of taking a bath, we can save water

1.My hair is short and curly--> I have ..........short and curly hair........................

2.Shall we stay at home and play computer game tonight?-->Let's...stay at home and play computer game tonight................................

3.Let's go to Ha Long Bay next summer vacation-->What about.......going to Ha Long Bay next summer vacation................................

4.London is smaller than Tokyo-->Tokyo is....bigger than London...................................

5.Where does she come from?-->Where is.she from ?.........................

6.What about talking some photos-->Why...don't wwe take some photos?.............................

7.What about going to Dam Sen park?-->Let's....go to Dam Sen park................

8.She plays badminton twice a week.-->How often.....does she play badminton ?.............

1. We (wait) for her for 30 minutes.
=>We have been waiting for her for 30 minutes

2. She (go) out since 5 a.m.
=>She has been going out since 5 a.m

3. They (not eat) anything all the morning.
=>They haven't been eating anything all the morning

4.  The street is full of water because it (rain) for 3 hours.
=>The street is full of water because it has been raining for 3 hours

5. She looks very exhausted because she (work) all night.
=>She looks very exhausted because she has working all night

6. I (read) this book since last night.
=>I have been reading this book since last night

7. She (chat) with her friend all the day.
=>She has been chating with her friend all the day

8. He (talk) on the phone for hours.
=>He has been talking on the phone for hours
9.  She (cycle) for 2 hours and she is very tired now.
=>She has been cycling for 2 hours and she is very tired now
10. We ( not write ) to teach us other for 6 months
=> We have been writing to teach us other for 6 months

            

1. It's getting dark. Let's turn ............... the light to study. (A. off / B. on / C. up / D. in)

2. The opposite of " hard " is ............... (A. busy / B. good / C. lady / D. lazy)

3. I .......... to a native speaker of English before. (A. have never talked / B. is talking / C. talked / D. will talk)

4. This robot .......... our faces when the scientists improve it. (A. guard / B. make / C. do / D. will be able to recognize)

5. He is looking ........... his keys because he has lost them. (A. after / B. at / C. for / D. up)

số cây đã trồng là :

180 : 100 x 45 = 81 ( cây )

số cây còn phải trồng là :

180 - 81 = 99 ( cây )

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