问题补充：
At times, parents find it difficult with their teenage children.
A. talk
B. talked
C. talking
D. to talk
答案：
A. talk
B. talked
C. talking
(答案→)D. to talk
解析：句意:有时候，家长们发现与他们的孩子交流是困难的。本句中所使用的结构为find +it +adj.+to do sth. 发现做某事是…的。在该句型中it 是一个形式宾语，真正的宾语是后面的动词不定式。故选D。
