中年: middle age...
伺机: to wait for an opportunity, to watch for one's chance...
未知数: unknown quantity...
常用: in common usage...
大爷: (coll.) father's older brother, uncle, term of respect for older man...
序言: preface, introductory remarks, preamble, prelude...
期望: to have expectations, to earnestly hope, expectation, hope...
水库: reservoir...
公路: highway, road...
继续: to continue, to proceed with, to go on with...
