を中心に => focused on; centered on~ N2
~のぼる  => To increase N2
Reach level
ざるを得ない => cannot help (doing); have no choice but to ~ N2
ざるを[得「え」]ない => Only A is left to do/can be done N2
(Not)only, (Not) even
~をきんじえない(~を禁じ得ない) => can't help but; can't refrain from ~ N1
得る => can; to be able to; is possible to~ N2
... おぼえはない => don't remember... N3
Position, perspective
じつをいうと => Frankly speaking N2
Story topic
からつくる/でつくる => made from; made with N4
つつある => to be doing; to be in the process of doing ~ N2
...を...みる => judging from; seeing that ~ N4
Deduce
...を...にする => to make something ~ N4
Purpose, target