Một đoàn tàu rời ga chuyển động thẳng nhanh dần đều. Sau 20s đạt vận tốc 36km/h.
a. Tính gia tốc của đoàn tàu.
b. Sau khi chuyển động được 40s thì đoàn tàu chuyển động thẳng đều trên đoạn đường tiếp theo trong thời gian 20s. Vẽ đồ thị vận tốc-thời gian (v-t) của đoàn tàu sau 60s chuyển động.
Mọi người giúp mình với ạ, mình đang cần rất gấp!!! Cảm ơn trước ạ :3
1. I can't be sure that Susan will help me because she is always busy.
RELY I can't ................... me because she's always busy.
2. The athlete wasn't successful in breaking the world high jump record.
VAIN The athlete tried ........................ the world high jump record.
3. He appears to be fighting with that man over there.
AS IT looks ...................... with that man over there.
4. Derek did not become a professional actor until he was forty.
TOOK Derek was forty ........................... acting professionally.
5. She wrote that book during her summer holiday.
WHILE IT was .............................. summer holiday that she wrote that book.
6. Our teacher demands that we hand in our homework regularly.
INSISTS Our teacher ................................ our homework regularly.
7. I don't know why Jane left in such a hurry.
CAUSED I don't know ...................................... in such a hurry.
Mọi người giúp mình với ạ!