  There exist six possible polarization modes of gravitational waves in general
metric theory of gravity, while two tensor polarization modes are allowed in
general relativity. The properties and number of polarization modes depend on
gravity theories. The number of the detectors needs to be equal to the number
of the polarization modes of the gravitational waves for separation of
polarizations basically. However, a single detector having great sensitivity at
lower frequency could be effectively regarded as a virtual detector network
including a set of detectors along its trajectory due to a long GW signal from
a compact binary and the Earth's rotation. Thus, time-varying antenna pattern
functions can help testing the polarizations of gravitational waves. We study
the effects of the Earth's rotation on the polarization test and show a
possibility to test the non-tensorial polarization modes from future
observations of compact binary mergers with ground-based gravitational
detectors such as Einstein telescope and Cosmic Explorer.
