一个电热器电阻为R，当它两端电压为U，通过时间t消耗电能为W，若使它消耗的电能为4W，下列方法正确的是[ ]

A. 电阻R不变，电压U不变，通电时间t变为原来的2倍

B. 电阻R减半，电压U增大1倍，通电时间t不变

C. 电阻R不变，电压U增大1倍，通过时间t不变

D. 电阻R减半，电压U不变，通电时间t不变

Microsoft’s COM is a software (146) that allows applications to be built from binary software components. COM is the underlying architecture that forms the foundation for higher-level software services, like those provided by OLE. COM defines a binary standard for function calling between components, a way for components to dynamically discover the interfaces implemented by other components, and a mechanism to identify components and their interfaces uniquely.

OLE is a compound (147) standard developed by Microsoft. OLE makes it possible to create (148) with one application and link or embed them in a second application. Embedded objects retain their original format and (149) to the application that created them. Support for OLE is built into the Windows and MacOS Operating Systems. A (150) compound document standard developed mainly by Apple and IBM is called OpenDoc.

（147）是（）

A.text

B.graphic

C.document

D.database