QUES: Most modern air defence systems are fairly mobile. Even the larger systems tend to be mounted on trailers and are designed to be fairly quickly broken down or set up. In the past, this was not always the case. Early missile systems were cumbersome and required much infrastructure; many could not be moved at all. With the diversification of air defence there has been much more emphasis on mobility. Most modern systems are usually either self-propelled (i.e. guns or missiles are mounted on a truck or tracked chassis) or easily towed. Even systems that consist of many components (transporter/erector/launchers, radars, command posts etc.) benefit from being mounted on a fleet of vehicles. In general, a fixed system can be identified, attacked and destroyed whereas a mobile system can show up in places where it is not expected. Soviet systems especially concentrate on mobility, after the lessons learnt in the Vietnam war between the USA and Vietnam. For more information on this part of the conflict, see SA-2 Guideline.

Contemporary air defence systems are usually what?
What is the answer?
ANS: mobile
QUES: Zhejiang consists mostly of hills, which account for about 70% of its total area. Altitudes tend to be the highest to the south and west and the highest peak of the province, Huangmaojian Peak (1,929 meters or 6,329 feet), is located there. Other prominent mountains include Mounts Yandang, Tianmu, Tiantai, and Mogan, which reach altitudes of 700 to 1,500 meters (2,300 to 4,900 ft).

What percent of Zhejiang is hills?
What is the answer?
ANS: 70%
QUES: Many kinds of clothing are designed to be ironed before they are worn to remove wrinkles. Most modern formal and semi-formal clothing is in this category (for example, dress shirts and suits). Ironed clothes are believed to look clean, fresh, and neat. Much contemporary casual clothing is made of knit materials that do not readily wrinkle, and do not require ironing. Some clothing is permanent press, having been treated with a coating (such as polytetrafluoroethylene) that suppresses wrinkles and creates a smooth appearance without ironing.

Permanent press materials have been treated with what?
What is the answer?
ANS:
a coating