Always use the safety belt and buckle your child in immediately after putting her in the booster seat. Even if your child's belted in safely, never leave her sitting in a booster seat unattended. Hold off on using booster seats without belts, such as the plastic cube-shaped seats you often see in restaurants, until your child's about 36 months old. These seats are not only dangerous because they lack safety belts, but they're also missing straps for securing the booster to a chair.
Noun. 1. trough-a narrow depression (as in the earth or between ocean waves or in the ocean bed). natural depression, depression-a sunken or depressed geological formation. swale-a low area (especially a marshy area between ridges).
The following illustration shows a cross-section through a transverse wave *. Switches below the main window can be used to label the following features: Crest - the highest point in the wave. Trough - the lowest point in the wave. Wavelength * - the horizontal distance between successive crests, troughs or other parts of a wave. Wave height - the vertical distance between the crest of a wave and its neighboring trough. This term is commonly used when describing water waves where the undisturbed surface is not easily determined.