Ответы
1-Have you been to London?- Yes, I have. I was there last summer.
2-She has never flown a kite.
3-The tourist has just crossed the square.
4-They crossed the street, turned to the left, and saw the boat.
5-We are very tired. We have just cleaned the house.
6-The students visited the Science Museum yesterday. They spent Science Night in the museum.
1) Have you been to London?- Yes, I have. I was there last summer. - last summer показатель прошедшего простого времени, поэтому в ответе на вопрос даем have (как в вопросе), а в полном ответе Past Simple
2) She has never flown a kite. - никогда не... - never - поэтому Present Perfect
3) The tourist has just crossed the square. - только что = just - поэтому Present Perfect
4) They crossed the street, turned to the left, and saw the boat. - простое перечисление действий в прошлом - Past Simple
5) We are very tired. We have just cleaned the house. - только что = just - поэтому Present Perfect
6) The students visited the Science Museum yesterday. They spent Science Night in the museum. - простое перечисление действий в прошлом - Past Simple