1. (try) to define happiness in a few words is very difficult.
2. Her sensations were difficult (describe).
3. Globbal warming is too important (forget) about it.
4. The climbers continued (walk) and could finally have a rest after a few hours.
5. Here we intend (demonstrate) that all circumstances should be taken into account.
6. In some countries parents make their children (work) long hours to get money.
7. Current studies show that the brain doesn't stop (grow) at the end of childhood.
8. Growing up means (assume) new reponsibilities.
9. Please don't forget in (fill) the form to apply.
10 He wrote a letter (express) his discontent with the situation.