请问这道题This is just ___challenging job all the students want to get.为什么这空a或the都可?

this is just this is just great请问为什么要有just?直接去掉可以吗 __ __ THIS MATHS PROBLEM IS ! is this your mum no,__ __ 请问I think this is Tom's book.对Tom's book画线提问 __ __ __ you think this is.前面三个空怎么填 翻译This is just the beginning just This __ is very interesting is this world just?is this world just or fair? This is just what I This one is just right. This is just a test. This is my own bag.=This is a __ __ __ __ 英语翻译This movie __is __ .He is __ it,__. This is her ruler同义句This ruler __ __ . OK...即填空：it is __ __ here this spring __ __ is Alice in this year?Grade Three. This house is used for __ (出租) This is __(lisa)classmate ,peter.