1.The teacher who volunteered (teach) in the poor village school was spoken highly of by many people.
【答案】 to teach
【解析】考查动词不定式。volunteer to do sth.自愿做某事，固定搭配，所以空处动词需用其不定式形式。故填to teach.
2.I wonder how ________ (solve) this problem.
【答案】to solve
【解析】句意：我想知道如何解决这个问题。分析句子结构，此空考查疑问代词+动词不定式结构作宾语；此处由 how可知，how to do“如何.....”，此语境是“如何解决这个问题”。根据分析，故填to solve.
