最适宜用来识别原始粒细胞的白细胞分化抗原(CD)的是()
A.CD33
B.CD3
C.CD19
D.CD41
E.CD44
参考答案:A
关于加速度,下列说法中正确的是( )
A.加速度的方向,总跟速度变化的方向相同
B.物体的速度随着加速度的减小肯定减小
C.只要物体的速度变化大,其加速度必定大
D.物体的速度等于零,其加速度必为零
Lei Feng ____ a lot of things for others in his life, people thanked him for what he _____.[ ]
A. did; had done
B. had done; had done
C. had done; did
D. did; did