ground: an area of interest, knowledge or ideas (兴趣、知识或思想的)范围,领域
He managed to cover a lot of ground in a short talk. 他在简短的谈话中涵盖了许多领域.
We had to go over the same ground(= talk about the same things again)in class the next day. 我们得在第二天的课上讨论同样的话题.
You're on dangerous ground(= talking about ideas that are likely to offend somebody or make people angry)if you criticize his family. 你要是批评他的家人可就惹麻烦了.
I thought I was on safe ground(= talking about a suitable subject)discussing music with her. 我以为与她一起讨论音乐是稳妥的.
He was back on familiar ground, dealing with the customers. 他又干起了与顾客打交道的老本行.
They are fighting the Conservatives on their own ground. 他们以保守党人自己的逻辑在和他们斗争.

narrow something↔down (to something): to reduce the number of possibilities or choices 把(可能性或选择)缩小(到);缩小范围
We have narrowed down the list to four candidates. 我们把范围缩小到四位候选者身上.

Go for: to be attracted by somebody/something; to like or prefer somebody/something 被...所吸引;(更)喜欢某人(或某事物)
She goes for tall slim men. 她喜欢瘦高个子的男人.
I don't really go for modern art. 我并不是很喜欢现代艺术.

at (your) ease: relaxed and confident and not nervous or embarrassed 舒适;自由自在;无拘无束
I never feel completely at ease with him. 我跟他在一起总感到不是很自在.