Объясните, , почему в данных предложениях именно такие формы глаголов? every year patriotic songs are heard everywhere in the usa on july 4. many questions were answered by the president at his annual conference last thuesday. the candeles were lighting on the birthday cake when sam returened from work. p.s. заранее !

Все так, предложения корректны:

Many questions were answered by the president at his annual conference last Thuesday.

Переводить на русский лучше в активе: "Президент ответил на многие вопросы во время ежегодной конференции на неделе во вторник".

Но форма глагола в пассиве: were answered by the president (были отвечены президентом)

У каждого времени и формы глагола есть свои маркеры. Если last Thuesday - значит Past Simple, если were answered by - значит Passive Voice. Если переводить дословно, то получится: "Много вопросов было отвечено президентом на ежегодной конференции в вторник", просто звучит некрасиво, потому переводить на русский лучше в активе.

The candeles were lighting on the birthday cake when Sam returened from work.

В переводе: "Свечи горели на именинном пироге, когда Сэм пришел с работы".

Предложение целиком относится к описывает одно короткое действие (Past Simple) во время продолжительного (Past Continuous) - все верно.

Every year patriotic songs are heard everywhere in the USA on July 4.

В переводе: "Каждый год патриотические песни слышны в каждом уголке Соединенных Штатов 4 июля".

Если Every year on July 4 - значит постоянное действие, берем Present Simple, если они слышны, а не сами слушают - значит Passive Voice.

Computers offer wonderful opportunities for everybody. Many teenagers enjoy using their computers. They make new friends and chat with them on the Internet.

But on the other hand, children who spend a lot of time at the computer, spend little time in the open air, they have virtually no real communication with peers. Many teachers in schools note the limited knowledge of children, lack of interest in reading books. Children sit in front of their PC or laptop (notebook) for hours and it’s bad for their eyes! They can’t stop playing cruel and silly games and become nervous and tired. The computer is sometimes a mere waste of time. Parents are concerned that the children using the Internet are not protected from negative information, which can be found on many sites. Computers are dangerous and addictive.

But besides many disadvantages in using the computer by children, there are of course some advantages too.

Regarding the education of children on the Internet, children can find all the necessary information that is not given even in the textbooks. The main condition - to be able to properly use the Internet resources, then the child will only benefit from the computer. Then the Internet helps greatly in children’s studies. They find the necessary information and ideas on the net and use them in their work. The computer helps them both to relax and to get a lot of new interesting information.      

To my mind, it’s a useful gadget.

Sierra ClubThe Sierra Club, founded in 1892, is one of the oldest conservation organizations in existence. (You can read more about it in the overview of the modern environmental movement.) With over 1.3 million members, this organization is one of the most effective and powerful at effecting changes in government and corporate America. Fighting for the preservation of land and forest, clean air and water, and a host of other issues, the Sierra Club is well-known and respected.National Audubon SocietyThe Audubon Society’s declared mission is “to conserve and restore natural ecosystems, focusing on birds, other wildlife, and their habitats for the benefit of humanity and the earth’s biological diversity” and since the late 1800s the organization has worked hard to achieve its mission. Interestingly, the original John Audubon, who created the foremost guide to North American birds, was not the founder, but did inspire the organization’s founders, namelyGeorge Bird Grinnell. Today bird conservation and Audubon are practically synonymous.World Wildlife FundThe iconic panda logo has made the WWF instantly recognizable to many people around the world. With 5 million members internationally and over 1.2 million in the States, this 45-year-old wildlife defense organization is going h2. h2ly promoting an emphasis on science, the WWF works to preserve nature and its creatures. From the organization’s website: “We are committed to reversing the degradation of our planet’s natural environment and to building a future in which human needs are met in harmony with nature. We recognize the critical relevance of human numbers, poverty and consumption patterns to meeting these goals.”
EarthFirst!Famously unapologetic, EarthFirst! came to national prominence in the 1990s. EarthFirst! is a little different. There’s no slick website. There’s no bureacracy. There are no members. They welcome any and all. The entire premise of this biocentric “movement” as it calls itself is to foster direct action. Founded in 1979 out of disgust at corporate environmentalism and “namby pamby” green action, EarthFirst!ers have famously gotten involved in green issues directly, sometimes breaking the law. Calling itself a priority, not an organization, the website explains: “Earth First! has survived attacks by moderates, would-be leaders and the agents of the system, remaining the most diverse, passionate, committed, and uncompromising group of environmental activists. Our direct actions in defense of the last wild places only seem radical compared to an entire paradigm of denial and control, where the individual is convinced they are powerless, and the organizations set up to protect the wilderness continue to bargain it away.”GreenpeaceGreenpeace began in 1971 when a group of activists put themselves directly in harm’s way in order to protest nuclear testing off the coast of Alaska. Believing that concerted action from ordinary people is the best way – according to their signature quote from Margaret Mead, theonly way – the organization has helped to stop whaling, nuclear testing, as well as leading efforts to protect Antarctica. Over 2.5 million members worldwide.

National Wildlife FederationThe National Wildlife Federation is dedicated to preserving animals in the United States and works with local agencies in the 48 contiguous states. It is one of the largest environmental organizations, with over 4 million members participating in grass-roots efforts on a variety of wildlife issues. The organization was actually founded by a cartoonist named Jay Darling (aka “Ding” Darling) in 1936 at the behest of President Franklin Delano Roosevelt.Natural Resources Defense Council (NRDC)According to the official website: “The Natural Resources Defense Council works to protect wildlife and wild places and to ensure a healthy environment for all life on earth.” The NRDC combines hundreds of active lawyers with over 1.2 million members to create direct and legislative change. The focus is on preventing climate change and saving endangered species, among other goals.1% For The PlanetIf you’ve shopped for anything organic or sustainable you’ve likely seen the 1% logo. With nearly 1,000 firms and companies now participating, 1% is helping corporate interests green their bottom lines by giving back to environmental causes. It’s a meaningful start.

Friends of Earth (FOE)Champions of healthy people, animals, plants, land, water and air, and devoted to stopping global warming, Friends of Earth supports a number of causes and is focused primarily on the United States, especially political and economic decisions as they affect public health and land conservation. In the 39 years in operation FOE has stopped over 150 dams from being built (among other achievements).