交響樂團入面既小提琴首席係點揀選出黎ga呢?

每一個聲部都有一個首席, 正常情況下是經試音(Audition)後得分最高的一位擔任, 試音可以是由樂團的指揮, 正副團長再加上非樂團的音樂界人士作評審, 至於第一小提琴的首席,又稱團長Concert Master可以是經試音, 或者由指揮或總監委任的, 視乎不同樂團的政策.

I assume you mean the concert master.
Nowadays, they are almost always appointed, instead of by auditions. The concert master has to have more than just skills, because his role is more than just playing the violin. (Concurrently, his contract is also different from the rest of the members, hence the ugly situation with Dennis Kim last year with HKPO.) The concert master has to have lots of experiences, preferably even experiences as concert master in other orchestras, strong character (could take the place of the conductor in his absence), and reliable (he answers directly to the conductor and director of the orchestra), hence, work experience counts too. Since he is required to play solo in many orchestral works, he is also expected to have solid experience as a soloist, not just as an orchestral player. Not all violinists in an orchestra is eligible to be a concert master, regardless of skills.
You could play really well and been playing with the orchestra your entire life, but if you haven't any work experiences (other than on the violin) or prior solo career, chances are you won't get chosen to be the concert master.

有時係Audition, 有時係選出黎(少數機會).
有時係指揮委派, 有時係有份起樂團既人做, 有時係輪流。