Нужно поставить в правильном времени. 1) i (to tell) just by the secretary that documents for my business trip (to prepare) now, but they (not to be ready) until the manager (to look through) them. 2) a new exhibition centre (to build) in our city lately and the number of people taking part in fairs and exhibitions there (to increase) from day to day. 3) the cars produced at this plant (to export) to different countries. 4) as it was noisy in the room i couldn't understand what (to discuss). later i found out that recent political events (to speak about). 5) i wondered why all the offers (not accept). the prices seemed quite reasonable because the company (to modify) the model before.

1) I have just been   told  by the secretary that documents for my business trip is being prepared   now, but they won’t  be ready  until the manager looks through   them. 
2) A new exhibition centre   has been built   in our city lately and the number of people taking part in fairs and exhibitions there are increasing  from day to day. 
3) The cars produced at this plant are exported   to different countries. 
4) As it was noisy in the room I couldn't understand what was discussed  Later I found out that recent political events had been spoken about.
5) I wondered why all the offers  were not accepted.The prices seemed quite reasonable because the company had modified  the model before