Question

________ the difficult maths problem, I have consulted Professor Russell several times.

A．Working out

B．Worked out

C．To work out

D．Work out

Answer 1

C

试题分析：考查非谓语动词的用法。句意：为了解出那道数学难题，我已经向Russell教授咨询过好几次了。非谓语动词中只有不定式可作目的状语，题干中缺少目的状语，故选C。
【知识拓展】不定式在句子中可作什么状语？
1）目的状语。To… only to (仅仅为了), in order to, so as to, so(such)… as to… (如此……以便……) 如：He ran so fast as to catch the first bus. 他飞快地跑以便赶上第一班车。I come here only to say good-bye to you. 我来仅仅是向你告别。
2）作结果状语，表事先没有预料到的，要放在句子后面。 如：What have I said to make you angry？我说什么让您生气了？He searched the room only to find nothing.他搜查了房间什么也没找到。
3) 表原因。如：I'm sorry to hear your father is ill听说你父亲病了很难过。