В чем разница между герундием причастием и инфинитивом???

Table manners are extremely important in Korea and Koreans rarely eat with their fingers. It is advantageous to learn the do's and dont's of Korean culture. They use a spoon and metal chopsticks which makes for an interesting learning experience! Spoons are used to eat from the many side dishes. Using both sets of utensils at the same time is considered to be bad manners, although leeway is given to foreigners and you will probably be the centre of a friendly tease. Soup is also a vital part of almost every meal. Other dishes include seafood, meat or poultry, greens, herbs and roots. Each person has his own rice and soup bowls but all other dishes are placed in the center of the table for everyone to partake of. Often in restaurants you will be required to sit at low tables on the floor, which takes getting used to. The good news is that many restaurants offer a normal table and chair set up.

All Korean cities have department stores which often contain a large supermarket in the basement. A lot of the food you will not recognize. However, there are many similar foods to what you are used to. Supermarket shopping is an interesting experience and sometimes trial and error is the only way to learn your way around. If you are really craving food from home there are a number of places in Seoul that specialize in international foods.

Как правильно:
1.Lavrov comes to (his,him) office at 9 o'clock in the morning.
2.Our businessmens learn English. They want to speak (its, it) well.
3.Our office manager often meets foreign bisinessmen and discusses prices for different goods with (their, them)?