Chứng minh phản chứng : Nếu a.b.c>0 thì ít nhất 1 trong ba số a , b , c là số dương?

In the old days, the vietnamese (dye) ________ their teeth black

1. This floor never looks dirty. It (clean) _________ everyday

2. The exercise (do) _________ tomorrow

3. The building (collapse) ________ last year

4. The tree ________ while a big wind ________ terribly. (collapse/blow)

5. The car _________ while the SH ________ (wash/polish)

6. It (rain) _______ along the coast of Thanh Hoa tomorrow morning

7. When she arrived, he ______ a strange girl (kiss)

8. When he was young, he _______ a trick on anyone that hated him (always play)

9. While she ______ his T-shirt, he ________ a newspaper (mend/read)

10. Don't call me at 8.00 tomorrow. I ________ a shower at the time (take)

1. This floor never looks dirty. It (clean) _________ everyday

2. The exercise (do) _________ tomorrow

3. The building (collapse) ________ last year

4. The tree ________ while a big wind ________ terribly. (collapse/blow)

5. The car _________ while the SH ________ (wash/polish)

6. It (rain) _______ along the coast of Thanh Hoa tomorrow morning

7. When she arrived, he ______ a strange girl (kiss)

8. When he was young, he _______ a trick on anyone that hated him (always play)

9. While she ______ his T-shirt, he ________ a newspaper (mend/read)

10. Don't call me at 8.00 tomorrow. I ________ a shower at the time (take)

1. This floor never looks dirty. It (clean) _________ everyday

2. The exercise (do) _________ tomorrow

3. The building (collapse) ________ last year

4. The tree ________ while a big wind ________ terribly. (collapse/blow)

5. The car _________ while the SH ________ (wash/polish)

6. It (rain) _______ along the coast of Thanh Hoa tomorrow morning

7. When she arrived, he ______ a strange girl (kiss)

8. When he was young, he _______ a trick on anyone that hated him (always play)

9. While she ______ his T-shirt, he ________ a newspaper (mend/read)

10. Don't call me at 8.00 tomorrow. I ________ a shower at the time (take)

1. This floor never looks dirty. It (clean) _________ everyday

2. The exercise (do) _________ tomorrow

3. The building (collapse) ________ last year

4. The tree ________ while a big wind ________ terribly. (collapse/blow)

5. The car _________ while the SH ________ (wash/polish)

6. It (rain) _______ along the coast of Thanh Hoa tomorrow morning

7. When she arrived, he ______ a strange girl (kiss)

8. When he was young, he _______ a trick on anyone that hated him (always play)

9. While she ______ his T-shirt, he ________ a newspaper (mend/read)

10. Don't call me at 8.00 tomorrow. I ________ a shower at the time (take)

1. She is sitting alone, and she (think) __________ about him

2. Now she (think) _________ that she should stydy harder

3. Stop running around. You (always/play) __________ so heartily

4. Look! The Greens (be) ______ happy

5. Look! Mary (do) ______ nothing

6. The anthem _________ proudly at the moment.

7. Listen! The door (knock) _________

8. Listen! She _______ her son. She __________ someone (not teach/phone)

Tìm các số nguyên để phương trình sau có nghiệm là các số nguyên:

x^2-(4+m)x+2m=0

Tìm các số nguyên để phương trình sau có nghiệm là các số nguyên: