A:CH4 + Cl2 →光 CH3Cl + HCl
B:
C:
D:
根据短文,选择正确答案。
Van and Ted are twin brothers. They look the same. They are English. They are eleven. They are in No.15 Middle School. They are new students in Class One, Grade One. Van sits in Row One. Ted sits in Row Three.
如图甲所示的地面清洁机器人,质量为3kg,要求对水平地面压强不超过3000Pa,机器人在水平地面运动时,所受推力与速度关系如图乙所示.(g取10N/kg).求: