Question

--- Did Cathy have problems ________ out the problems?

      ---Yes. I found her _________  on it for nearly half an hour.

A. work; to work    B. to work; working    C. working; working

Answer

C

【解析】句意：——凯西解决这些问题有困难吗？--——是的。我发现她做了将近半个小时。have problems(in) doing sth. 做某事有困难， find sb. doing sth.发现某人正在做或持续做某事，结合句意，答案为C。

点睛：(1) have problems/difficulty/trouble (in) doing sth. 都有“做某事有困难”的意思。

(2) find/see/hear 等词后既可以跟do也可以跟doing作宾语补足语，find/see/hear sb. do sth” 表示看到/听到某人做了某事，强调做过，发生过；或表示经常性、习惯性做某事；而“see/hear sb. doing sth”是看见/听见某人正在做某事，强调某一时间点正在发生的事情。例如：I saw him work in the garden yesterday. 昨天我看见他在花园里干活了。(强调"我看见了"这个事实) I saw him working in the garden yesterday.（强调"我见他正干活"这个动作） 昨天我见他正在花园里干活。