Question: Polarization is predictable from an antenna's geometry, although in some cases it is not at all obvious (such as for the quad antenna). An antenna's linear polarization is generally along the direction (as viewed from the receiving location) of the antenna's currents when such a direction can be defined. For instance, a vertical whip antenna or Wi-Fi antenna vertically oriented will transmit and receive in the vertical polarization. Antennas with horizontal elements, such as most rooftop TV antennas in the United States, are horizontally polarized (broadcast TV in the U.S. usually uses horizontal polarization). Even when the antenna system has a vertical orientation, such as an array of horizontal dipole antennas, the polarization is in the horizontal direction corresponding to the current flow. The polarization of a commercial antenna is an essential specification.
Is there an answer to this question: The polarization of what antenna is essential specification?

Answer: commercial antenna


Question: Some species of bacteria kill and then consume other microorganisms, these species are called predatory bacteria. These include organisms such as Myxococcus xanthus, which forms swarms of cells that kill and digest any bacteria they encounter. Other bacterial predators either attach to their prey in order to digest them and absorb nutrients, such as Vampirovibrio chlorellavorus, or invade another cell and multiply inside the cytosol, such as Daptobacter. These predatory bacteria are thought to have evolved from saprophages that consumed dead microorganisms, through adaptations that allowed them to entrap and kill other organisms.
Is there an answer to this question: Why are certain bacteria called predatory?

Answer: bacteria kill and then consume other microorganisms


Question: Brasília is known as a departing point for the practice of unpowered air sports, sports that may be practiced with hang gliding or paragliding wings. Practitioners of such sports reveal that, because of the city's dry weather, the city offers strong thermal winds and great "cloud-streets", which is also the name for a manoeuvre quite appreciated by practitioners. In 2003, Brasília hosted the 14th Hang Gliding World Championship, one of the categories of free flying. In August 2005, the city hosted the 2nd stage of the Brazilian Hang Gliding Championship.
Is there an answer to this question: What is the name for paragliding in Brasilia?

Answer: unanswerable


Question: As of 2004[update], 2532 telephone main lines are in use, a mix of analog (2500) and digital (32) circuits. Satellite communications services are planned.[citation needed] There is one locally based radio station (Radio Norfolk 89.9FM), broadcasting on both AM and FM frequencies. There is also one TV station, Norfolk TV, featuring local programming, plus transmitters for Australian channels ABC, SBS, Imparja Television and Southern Cross Television. The Internet country code top-level domain (ccTLD) is .nf.
Is there an answer to this question: How many local radio stations does Norfolk Island have? 

Answer:
one