If they go to washington, they (see) the white house. if she (have) a hamster, she would call him fred. if he gave her a sweet, she (stop) crying. if he (arrive) later, he will take a taxi. we would understand him if he (speak) slowly. andy (cook) dinner if we buy the food. i will prepare breakfast if i (wake up) early. if they shared a room, they (fight) all day long. if you hate walking in the mountains, you (enjoy / not) the tour. janet would go jogging if she (have / not) to do her homework. надо

1)will see
2.had
3.would stop
4.arrive
5.spoke
6.will cook
7.wake up
8.Would figh
9.will not enjoy
10.Did not have

1.с) Слово начинается на гласную, поэтому артикль an.
2.d) Здесь идет Present Perfect, в этом времени используется выражение been to.
3) c) Present Continous требует вс глагола to be в формах am, is, are.
4) b)  Выражение.
5) d) Выражение.
6) c) Используется множественное число, без основного глагола.
7) b) Past Passive требует вс глагола и основного глагола в 3-ей форме.
8) d) Короткое прилагательное в превосходной степени.
9) b) В течении  трех лет.
10) a) Past Continous.
11) с) Выражение.
12)d) Who- 3 
13) b) Present Perfect.
14) b)Выражение.
15)d) Present Continous.
16)c) Future
17)d) if+Present Simple+will...
18)b)
19)a) if+Past Simple+would...
20)b)

Learning a foreign language is not easy. It is a long and slow process that requires a lot of time and effort. Nowadays it is especially important to know foreign languages. ..some people learn languages because they need them for work, others go abroad, for others, learning languages is a hobby. ..everyone who knows foreign languages can communicate with people from other countries, read foreign writers in the original, which broadens their horizons. It is not surprising that many intellectuals and educated people are polyglots. I am learning English. ..nowadays English has become the most important language in politics, science, trade and cultural relations. More than 300 million people speak it as their first language. ..native English speakers live in the UK, United States of America, Australia and New Zealand. English is one of the official languages in the Republic of Ireland, Canada, and the Republic of South Africa. ..English is one of the official languages of the United Nations and other political organizations. Half of the world's scientific literature is written in English. It is the language of computer technology. ..to know English today is absolutely necessary for every educated person, every good specialist. English is a wonderful language. This is the language of great literature. ..it is the language of William Shakespeare, Jonathan Swift, Walter Scott, Charles Dickens. The great German poet Goethe once said: "He who does not know a foreign language does not know his own." ..therefore, to understand yourself and the environment, you need to learn foreign languages. 2. ask a few questions