a) Mr. Jones has worked/has been working for my father for 15 years.

b) Juliette started to teach an the school in 2009

c)The girls asked the teacher some guestions

d)Christopher wanted to buy the iPod yesterday

e)Mathew travelled to Germany 3 weeks ago

f)Hector has already understood the problems .

g)Alice has drunk a glass of orange juice.

h)She has not washed her hair this morning

i)Nuria enjoyed the school play last Saturday

j)Lawrence has taken the books to the library