A:t1、t3两时刻速度相同
B:t2时刻速度和加速度均为零
C:t1、t3两时刻加速度等值反向
D:若t2=2t1则可以求出物体的初速度为8 m/
⑴浓硫酸⑵浓盐酸⑶粗盐⑷生石灰⑸氢氢化钠⑹酒精
⑴Is it hot?____ A. It's on the second floor.
⑵What's the weather like in Beijing?____ B. It's warm and sunny.
⑶Where is the library?____ C. Yes,we do.
⑷What time is it?____ D. No,it isn't.
⑸Do you have a computer room?____ E. It's 6 o'clock.
His brother____ ____ ____ ____in the PE test.