a part of, the part of, part of, parts of的区别是什么?These elements become 【part of】 the interstellar gas and dust.这些元素成了星际气体和星际尘埃的一部分.请问：这里用part of对不对?为什么?

a part of the part of part of 区别 part of the time southern part of the the better part of a decade England is a part of the A small part of play the part of 与play a part of一样吗 is part of 和is a part of 的区别?Filing the clippings is part of the daily work of a secretary.此句话中应该是 is part of 还是 is a part of In this part of the Part Of The List 歌词 Part Of The Process 歌词 I feel like part of the group now 是不是病句?我认为应该是a part What's the tastiest part of a McDonalds?The box. The prelude is a part & parcel of the contract only ------the surface of the earth is land.A.part of B.a part of C.parts of D.part 选什么为什么 PART OF part of in a fun part of