In the following essay, each blank has four choices. Choose the best answer and write-down on the answer sheet. Microwave communication uses high-frequency 29 waves that travel in straightlines through the air. Because the waves cannot 30 with the curvature of the earth, they can be 31 only over short distance. Thus, microwave is a good 32 for sending data between buildings in a city or on a large college campus. For longer distances, the waves must be relayed by means of "dishes" or 33 . These can be installed on towers, highbuildings, and mountain tops.
Microsoft's COM is a software architecture that allows applications to be built from binary software components. COM is the underlying 48 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 49 standard developed by Microsoft. OLE makes it possible to create 50 with one application and link or embed them in a second application. Embedded objects retain their original format and 51 to the application that created them. Support for OLE is built into the Windows and MacOS Operating Systems. A 52 compound document standard developed mainly by Apple and IBM is called OpenDoc.
=2×10-5s=20μs。
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