I AM WORK IN THE COMPANY OF NON-MUSLIMS IN SINGAPORE. SOMETIME WE HAVE ALL THE MANAGERS MEETING, AND DURING LUNCH TIME, MOST OF TIME WE LUNCH OR HAVE DINNER AT NON-HALAL RESTAURANT. IS IT OK THAT I TAKE ONLY FISH AND VEGETABLES? IT IS VERY DIFFICULT TO CONVINCE THEM THAT I DON'T TAKE NON-HALAL FOOD AND THEY ARE NOT UNDERSTANDING.

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
You have to restrict yourself to eating fish and vegetable as long as the other foods contain forbidden items such as dead meat or pork.
You should not eat anything that is not Halal (lawful) even though the administration of your company does not agree with that. You have to avoid sitting at a dining table where forbidden foods or drinks are served.
A Muslim is obliged to keep away from all things, which are prohibited in Sharia.
Since whoever commits the doubtful things surely he will end up committing illegal things since it is very hard to avoid them, so how about a person who actually commits Haram? One should not adopt the policy of expansion in courtesy in the matters of Halal and Haram.
Did you not notice that the Seikh wears his turban every where in the world? Do you not see the dissolute women almost naked moving in public places? Since people who are following a bad path stick to their rituals and habits aren't we (who have chosen the right path) required even more to be obedient to Allah's commands? We ask Allah to help us to follow His path and to act as it pleases Him.

Allah knows best.