Начерти 1)отрезок АВ,длина которого равна половине длины отрезка 1дм; 2)отрезок СD,ДЛИНА ПОЛОВИНЫ КОТОРОГО РАВНА 2СМ

Помогите пожалуйста срочно нужно... В этом тексте нужно найти инфинитивы,а я не понимаю ,что это.

For most British families, this is the most important festival of the year. This is the day when many people are travelling home to be with their families on Christmas Day. If you try to catch a train on 24th December you may have difficulty in finding a seat. There are a lot of traditions connected with Christmas but the most important one is the giving of presents. Family members wrap up their gifts and leave them at the bottom of the Christmas tree to be "bound on Christmas morning. At some time on Christmas Day the family will sit down to a big turkey dinner followed by Christmas pudding. In the afternoon they may watch the Queen on the television as she delivers her traditional Christmas message to theUnited Kingdomand Commonwealth. Then they enjoy a piece of Christmas cake or eat a hot mince pie. On the Sunday before Christmas many churches hold a service where special hymns are sung. Sometimes singers can be heard on the streets as they collect money for charity. Most families decorate their houses with brightly-coloured paper or holly, and they usually have a Christmas tree in the corner of the room, glittering with coloured lights and decoration. 26th December is also a public holiday, called Boxing Day. This is the time to visit friends and relatives or be a spectator at one of the many sporting events.