问题
单项选择题
The research scientists often meet with problems_____new types of instrument for their solution.
A．requiring
B．required
C．to require
D．being required
答案
参考答案：A
解析：此题应选现在分词requiring，在句中作定语，修饰problems，相当于定语从句…problems which require...，因为它们在逻辑上是主动关系，所以应选现在分词。句意为：“科研人员常常遇到需要新型仪器才能解决的问题。”