Ответ: it
(has been) long since I ( wrote) a letter to you. At last I (am) in
London. The weather (is) nasty. It (has been raining) all day today. I (
think) it always ( rains) on Sundays in London. Anyway, it (has rained)
every weekend since I ( came) to Britain three months ago. I (am getting)
used to it, but I ( find) it rather dull. But I (am enjoying) my stay
here as I (have made) a lot of friends here who ( come) from different
countries. Some of them (have been staying) here for a few years and (can speak)
English quite well. I (will introduce) you to them when you ( come)
here. All this time I (have been trying) hard to master my English and I (
think) I (have made) some progress. I (was not be able) to find the job I
(had been looking for). I (have been) to quite a number of cities but so far I (have not  found) anything suitable. My friend Peter who (is) German and (
came) here a year ago (has found) at last a job at a German-British
company. He ( promised) to help me because he (knows) that I (learnt) German for three years. I ( hope) to hear from you soon.