RT,题目如下 希望能有比较详细的分析过程，谢谢！
1.Linda's teacher was so mad _____ her because she made lots of mistakes in the test.
A.at B.in C.on D.about
2.—Is Jack in the library?
—Maybe.I saw him _____ out with some books just now.
A. going B. go C.to go D.went
3.Jack started to work at _____ early age because his family was very poor.
A.a B.an C.the D./
1. 没有答案，因为be mad with sb, be mad at(about) sth,
2. B, 因为see sb do/ doing, 这里因为说刚才出去，所以应该go, 而going表示正在出去，不符合逻辑
3。B ,因为是固定搭配，
1.选a，be mad at sb 生某人气，be mad about sth对···狂热，其他均无此搭配
2.选b，感官动词加doing一定要在说话时动作正在进行，即使是过去看见某人在做什么也要加原型。
3.选b，很早、很小就开始工作了，年龄并不确定，又是early，an是正确选项 。
1 选D be mad about sb 对某人生气、发怒
2选A see sb doing强调片段，带着几本书走，只是看到一瞬间而已。
3选B at an early age 在年轻时