Language Point 40

...spent an hour or two trying a great number of combinations, but he arrived at no result. (Para. 5)
Meaning : ...spent a couple of hours trying many, various combinations, but he made no success.
spend (time) doing something: pass the time doing sth.
He spent an hour each day exercising.

他每天花1小时运动。
Now more and more city adults spend their free time trying to improve themselves at school or college.

现在城市里越来越多的成年人利用业余时间到学校或大学去充电。
Compare: spend (time) on something
He doesn't spend much time on his homework .

他花在作业上的时间不多。