A:CH3Cl
B:C2H6
C:C2H5OH
D:CH3COOH
Water pollution influences the look of our city and even worse, it _______ our health.
在半径为r、电阻为R的圆形导线框内,以直径为界,左右两侧分别存在着方向如图甲所示的匀强磁场,以垂直纸面向外的磁场为正,两部分磁场的磁感应强度B随时间t的变化规律分别如图乙所示.则0〜t0时间内,导线框中( )
《尚书·洪范》记载当时的政务时说:“一曰食,二曰货。”“货”在八种政务中排在第二,仅次于“食”。这反映出当时( )
Poor Danny! It is cold outside. Please close the door.