11.1.1(单项选择题)甲、乙两人射击,A、B分别表示甲、乙两人射中目标则事件AB表示() A.两人都没射中 B.至少一人没射中 C.两人都射中 D.至少一人射中 (难度:A;水平:a) 11.1.2(单项选择题)设A与B是相互独立的事件,已知P(A)=,P(B)=,则P(A+B)=() A.1 B. C
Heart as Strong as Iron\ Techniques Checklist: Use of a centrifuge Equipment: Disposable UV-Vis cuvettes 1-mL capacity) .Pipetmen: 20P, 100 P, 1000 P .Pipet tips Eppendorf tubes (safe-lock) .Hot plate
Polar coordinates极坐标 The position of a point P in polar coordinates is defined by the radial coordinate r and the angular coordinateθ. 一点P的极坐标用径向坐标r和角坐标θ表示 P(r,0) displacements:位移:urue strains:应变: