如右图所示，一带正电小球穿在一根绝缘的粗糙直杆上，杆与水平方向成θ角，整个空间存在着竖直向上的匀强电场和垂直于杆方向斜向上的匀强磁场，小球沿杆向下运动，在A点时的动能为100 J，在C点时动能减为零，B为AC的中点，在运动过程中（   ）

A．小球在B点时的动能为50 J

B．小球电势能的增加量等于重力势能的减少量

C．小球在AB段克服摩擦力做的功与在BC段克服摩擦力做的功相等

D．到达C点后小球可能沿杆向上运动

UML-based tools are often used for J2EE/.NET application analysis and design, both because UML’s object orientation is ideal for the J2EE/.NET implementation (66) and because of the expanding scope and complexity of today’s enterprise endeavors. (67) the approaches diverge at the coding/implementation phase, a common set of analysis and design techniques applies to both J2EE and.NET.

The use of a virtual, machine (VM) architecture is also common to J2EE and .NET. Application development tools (68) intermediate-level code instead of platform-specific binary code, which means the VM interprets that code in real time or performs Just-In-Time (JIT) compilation; the Microsoft VM always runs JIT-compiled code. This VM-based model results in (69) -independent applications and is conducive to the late-binding technique that’s (70) to the OO approach.

（67）（）

A.Although

B.However

C.But

D.Thus