1_what is the difference 成为 and 当？（to become) 成为=to become 当, 当作 maybe you mean be regarded as, be used as, eg, 我把她当作我的母亲。 （she is actually not my mother, but she's so nice , so i take her as my second mother） or you mean this situation : 他想 成为/当 一个老师。 this moment it's the same. 2_what does mean 份子in this sentence？ 一份子=a member of = （成为。。。）一员 3—过半客户是欧美品片卑？ -_-||| it's not 品片卑， but is 品牌， brand here are mistakes in the sentence, 客户=clients， are the people， but 品牌 is brand， they are not the same, can't be connected with “BE 是” 4_从国内一流大学 一流 XX = the top XX of XX from the top universities in china,.... 5—what does mean 端in this sentence?（and please tell me the meaning of whole of sentence) sorry, i have sth emergent , have to leave for a moment, again you later :)

1.成为 can be a bit more formal than 当 when they all mean "to become" 2.份子 means being a member of the company（风腾） 3.it's 品牌(pái) i guess, which means brand. for example, Nike is a well-known brand. Nike 是一个著名的品牌。 as to the meaning of the sentence, it's not a correct sentence so i cant tell u what it means exactly. 4.流 here means level or class, 一流 means first-class or first-rate. the whole sentence means (well actually it's not a complete sentence) - from the first-class domestic university. guess the whole sentence should be like - someone graduated from the first-rate university in China. 5.it's a verb, like hold or bring something with both hands. the sentence means ( not a complete sentence as well, lacks the subject) - maybe (u) have to start from serving the coffee (denpending on the different contexts, it may mean like u have to start from some very simple or basic job like a waiter or something) P.S. would be easier for us to explain it more clearly if u show more context, since the meaning of some phrases can be different according to the different context.

5—what does mean 端in this sentence?（and please tell me the meaning of whole of sentence) 可能都要从端咖啡做起。