Поставить частичку tо там, где это необходимо.It is not an easy

Поставить частичку tо там, где это необходимо.

It is not an easy thing ... learn a foreight language.
We have ... practise very hard and try ... learn as many words as possible.
We can't ... speak any language without words.
What do you ... think is the best way ... memorize new words?
First of all, you should ... repeat the words you've learnt as possible.
Secondly, you ought ... listen to the material you are learning, becouse words are not always pronounced according to the rules of reading.
And finally, it's a good idea ... study words defore you go to bed.