Giúp mình vs các bạn ư i

EXERCISES: rewrite the sentences 1, How long is it since he bought the computer? When..... 2, I have never talked to the headmaster before It is... . 3, The last time we went to LONDON was two years ago We haven't..hæ:..ta.. 4, I last went to MY SON three years ago ja.txa.dflat,S It.. ...