giúp em với em cảm on nhiêuuu
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Đề 3
1 A
2 B
3 A
4 D
5 B
6 A
7 D
8 C
9 B
10 C
II
11 are
12 arrived
13 have lived
14playing
15 to ride
16 A
17 D
18 B
19 D
1. ……………………Does the film begin………..…………………………….. (the film/ begin) at 7.00 or 8.00?
2. The art exhibition (open) ………opens……………… on 5 May and (end) ………ends…………… on 4 July.
3. The train (leave) …………leaves………… Saigon at 2.30 and (arrive) …………arrives……. in Nha Trang at 8.00.
4. We (start) ………start……………. our work on Tuesday and (finish) ………………finish………. on Sunday.
5. Next Saturday (be) ……………is……………….. thirteenth.
6. When …………………does this TV program finish…………..…………………………….. (this TV program/ finish)?
7. Where ………………do they collect…………..…………………………….. (they/ collect) garbage?
8. My train ………………leaves…………….. (leave) at 8.00, so I need to be at the station by 7.45.
9. What time …………………………does she finish…..…………………………….. (she/ finish) your work tonight?
10. “What time ………………does your train leave……………..…………………………….. (your train/ leave) tomorrow?”
– “Seven o’clock in the morning. It (get) ………gets……………………..into Paris at eleven.”
Vì điểm M nằm giữa 2 điểm O và N nên ta có:
⇔ OM + MN = ON
Thay số : 3 + MN = 7
MN = 7 - 3
⇔ MN= 4 cm.
Vì A là trung điểm của MN nên ta có:
⇔ MA = AN = MN/2
Thay số : MA = AN = 4/2 = 2cm
⇔ Điểm M nằm giữa 2 điểm O và A nên ta có:
⇔ OM + MA = OA
Thay số : 3 + 2 = OA
⇔ OA = 5cm.
Vậy OA = 5cm.
Các cao nhân giúp em với ạ. Em chân thành cảm ơn.
1_Michael wants to win the race; therefore he is training hard.
=> Michael is ………training hard because he wants to win the race……………………………………………..
2_Let’s make some posters on energy saving .
=> What about ……making some posters on energy saving……………………………....?
3_Why doesn’t she take shower to save water ?
=> We suggest ………………………that she take shower to save water……………..
4_Let’s decorate our class more beautifully.
=> I suggest our……class being decorated more beautiful ………………………….
5_I suggest turning off the light when we go out.
=> Why not………………turn off the light when we go out…………………..………?
6_Nobody has cleaned this room so it is very dirty.
=> Since……nobody has cleaned this room, it is very dirty……………………………………………………..………………
7_Jane’s dog died so she was sad.
=> As……her dog died, Jane was sad.…………………………………………………….………………
Đọc tiếp
17. My mother does housework every day. She is a__housewife__( house)
18. Her brother works on the farm. He is a __farmer____.( fram)
19. Mr Dung drives carefully . He is a good__driver___.(drive)
20. We go __shopping__ with friends on the weekend (shop)
\(a^3b-ab^3=ab\left(a^2-b^2\right)=ab\left(a^2-ab+ab-b^2\right)=ab\left(a-b\right)\left(a+b\right)\)
Với a hoặc b chẵn \(\Leftrightarrow ab\left(a-b\right)\left(a+b\right)⋮2\)
Với a và b lẻ \(\Leftrightarrow\left(a-b\right)⋮2\Leftrightarrow ab\left(a-b\right)\left(a+b\right)⋮2\)
Vậy \(ab\left(a-b\right)\left(a+b\right)⋮2,\forall a,b\left(1\right)\)
Với a hoặc b chia hết cho 3 thì \(ab\left(a-b\right)\left(a+b\right)⋮3\)
Với \(a=3k+1;b=3q+1\Leftrightarrow\left(a-b\right)=3\left(k-q\right)⋮3\)
\(\Leftrightarrow ab\left(a-b\right)\left(a+b\right)⋮3\)
Với \(a=3k+1;b=3q+2\Leftrightarrow\left(a+b\right)=\left(3k+1+3q+2\right)=3\left(k+q+1\right)⋮3\)
\(\Leftrightarrow ab\left(a-b\right)\left(a+b\right)⋮3\)
Mà a,b có vai trò tương đương nên \(ab\left(a-b\right)\left(a+b\right)⋮3,\forall a,b\left(2\right)\)
\(\left(1\right)\left(2\right)\Leftrightarrowđpcm\)
Ta có : a3b -ab3
=a3b -ab -ab3 +ab
=ab (a2 -1) -ab (b2 -1)
=ab (a-1)(a+1) -ab (b-1)(b+1)
Vì a (a-1)(a+1) là 3 số tự nhiên liên tiếp nên chia hết cho 6 .Tương tự b (b-1)(b+1) cũng chia hết cho 6
=> a3b -ab3 chia hết cho 6 (đpcm )