Trade fairs offer direct contact with current and potential customers and a venue to launch products that will reach opinion-formers (such as journalists).
展销会提供了与现有及潜在客户的直接接触，上市会则可以让媒体了解（例如记者）。
2
Through electrostatics and examples of low-frequency alternating current and direct-current circuit, the problem of zero potential point is queried and clarified.
通过静电学、低频交流、直流等电路实例，质疑了电势零点问题，并对此进行了澄清。
3
The principle and method for testing surface crack through directcurrentpotential difference are introduced.