spend something on something
spend something in doing something(这里的in可以省略)
但在长期的教学实践中，我发现有不少小伙伴仍然在用spend something on doing something，如
In order to get good grades, we should spend a massive amount of time on studying our subjects. ×
这显然是把on something和in doing something混用了，有“司马光砸光(缸)”之嫌。尽管有极少数词典说spend something on doing something也正确，但是绝大多数词典或权威教材不这么认为。所以，为了保险起见，还是应该坚持用spend something on something或spend something in doing something，来看两个例子：
【例】spend a lot of time on a project 花很多时间进行某项目/spend a lot of time (in) explaining a plan 花很多时间解释某方案
(例句来源：Oxford Advanced Learner’s English-Chinese Dictionary)
所以，刚才的句子应该这样写：
In order to get good grades, we should spend a massive amount of time on our subjects. √
或
In order to get good grades, we should spend a massive amount of time in studying our subjects. √
若一篇文章中spend出现的次数较多，那么可以用expend来替换，expend和spend基本同义，使用方法也基本相同，但比spend更加正式，会使用的考生也较少，如果使用得当，可以给自己的文章增添一点高大上的气息。来看两个例句：
【例】We’ve already expended too much energy on this project. 我们已经在这个工程上耗费了太多的精力。
(例句来源：MacMillan English Dictionary – American)
【例】Manufacturers have expended a lot of time and effort trying to improve computer security. 制造商们已经花费了很多时间和精力来尽力改善计算机安全。
(例句来源：Longman Dictionary of Contemporary English)
