diversify (v)
/daɪˈvɜː.sɪ.faɪ/ 

to broaden, to make more varied

source (n)
/sɔːs/

a person, place, or thing that provides something that you need or want

smooth (a)
 /smuːð/

causing no difficulty, problems, or delays

quality (n)
/ˈkwɑː.lə.t̬i/

how good or bad something is

prerequisite (n)
 /ˌpriːˈrek.wɪ.zɪt/

something that is required or necessary as a prior condition

obtain (v)
 /əbˈteɪn/

to get something that you want or need, especially by going through a process that is difficult

maintain (v)
 /meɪnˈteɪn/

to continue to have; to keep in existence

function (v)
/ˈfʌŋk.ʃən/

to perform tasks

everyday (a)
/ˈev.ri.deɪ/

routine, common, ordinary

essential (a)
 /ɪˈsɛnʃl/

extremely important or necessary

enterprise (n)
/ˈen.t̬ɚ.praɪz/

a business company or organization

stationery (n)
/ˈsteɪ.ʃə.ner.i/ 

the things needed for writing, such as paper, pens, pencils, and envelopes

mail order (n)
/meɪl ˈɔːr.dɚ/

a way of buying goods in which you order them by post, telephone, or the Internet and they are posted to you

deposit (n)
/dɪˈpɒz.ɪt/

an amount of money that you pay as the first part of the total payment for something

monthly payment (phrase)
/ˈmʌnθ·li ˈpeɪ·mənt/

the amount paid each month towards the principal and interest amount of a loan

free delivery (phrase)
/friː dɪˈlɪv.ər.i/

there is no cost for transporting the goods to the buyer

extra cost (n)
/ˈek.strə kɒst/

the additional amount of money needed to buy, do, or make something

various service package (phrase)
/ˈver.i.əs ˈsɜː.vɪs ˈpæk.ɪdʒ/

related group of dealing with a customer in a shop, restaurant, or hotel by taking their order, showing or selling them goods

wholesaler (n)
/ˈhoʊlˌseɪ·lər/

someone whose job is to sell large quantities of goods to shops or small businesses

increase (v)
/ɪnˈkris/

to (make something) become larger in amount or size