بِ is used In the first sentence to mean that you feel -of- cold.. so you put it before the something that you feel of.. In the second sentence to mean the same of the first, because it means that you're welcome -of -your entering.. so the suffix بِ used to express what are you doing with the verb.. also the same in the last sentence, it means in question - do you enjoy the film - or - have you felt enjoyed -of- this film - you can even translate as - I used the film to enjoy - Another uses: كتبت بالقلم it means that you used the pen to write لعبت بالكرة it means that you used the ball to play سافرت بالقطار I traveled by the train - I used the train to travel -

Bi - بِ it's usually attached to nouns (Bi-al kalam (Bil kalam) / Bi-al makan (Bil makan) ), and it used to show what does a person use in order to do something. for example in English we say (What language do you speak - I seapk Arabic) which means in Arabic (What do you use to speak - I use Arabic to speak) - What -> Mada / ماذا What do you use to (verb) -> Bi-mada (verb) / بماذا - (for male) What do you use to (drink) -> Bi-mada (Tachrabo) / بماذا تشرب I drink using a cup -> Achrabo Bi-al kaassi (Bil kaassi) / أشرب بالكأس - (for female) What do you use to (drive) a cake -> Bi-mada (Takodina) asayara / بماذا تقودين السيارة I drive using my hands -> Akodo Bi-yadaya / أقود بيدي

Hi, Raym. It is a preposition, and those particular verbs require its use. In English, I believe we would call them prepositional verbs. I hope that helps! Good luck!