The development of mechanical timepieces spurred the search for more accurate sundials with which to regulate them.
这个句子是一个定语从句,然后which是sundial,them是timepieces ,这个句子还原应该是rugulate timepieces with accurate sundials.这样就没有主语了。
...trouble crossing the street to meet the new neighbor. 我觉得可以把不定式看作crossing the street的目的状语。二者再共同作trouble后被省的in的宾语.这样看意思说得通。但若把不定式提到have trouble前,就成了“为了亲近邻居,我们在穿...