Paul学汉语是为了来中国做生意。(Paul xue han yu shi wei le lai zhong guo zuo sheng yi.) “为了” is often used in the first clause of a compound sentence to indicate the aim, the second clause indicates the action taken to achieve the aim, e.g: 为了学汉语，很多外国人来到中国。 Sometimes the action that is taken can be put before its aim introduced.
他没有学过汉语，可是口语很好。(ta mei you xue guo han yu, ke shi kou yu hen hao.) “可是” is a conjunction expressing transition. It’s used between two clauses, e.g: 我听说过这个名字，可是不知道是谁。
我要一边听歌，一边学汉语。(wo yao yi bian ting ge, yi bian xue han yu.) In Chinese, two “一边” are often used in conjunction to indicate doing two or more actions at the same time, e.g: 妈妈一边做饭，一边和客人聊天。
我要先在这儿学习半年，然后在中国工作。（wo yao xian zai zhe er xue xi ban nian, ran hou zai zhong guo gong zuo.） In Chinese, the adverb “先” is often used before the adverb “然后”, to indicate the sequence of two events. The frist clause expresses the action that has been done first or the event that has taken place first..