1.to buy
2.work 解析：make sb.do sth.不定式在使役动词和感官动词后去掉 to 作宾补.
3.waiting.解析：keep sb.doing （使某人持续做某事）是固定搭配.
4.to clean.解析：被动语态中,不定式作宾补,to 要还原,即 sb.is made to do sth.（某人被迫做某事）.
5.groups ,小组,这里指许多个小组.
6.especially,副词,“尤其是”.
7.有时口语或非正式场合 it 会用别的词代替.那有没有make sb doing sth 或 keep sb do sth?我没有见过 make sb. doing 或 keep sb. do 这两个结构。但有：make / keep sb. done，用过去分词作宾补是可以的。e.g.He spoke aloud to make himself heard. Are your employees and your products and services doing their part to keep your customers satisfied?