(a) With inf. modifying a verb and expressing purpose: in order to (do sth.), for the purpose of (doing sth.)
(b) with inf. modifying a ppl. as adj.: to (do sth.); dight unto seilen, ready to sail;……
With selected complementary infinitives in verb phrases: to (do sth., be sth., etc.);—sometimes with intervening element between the verb and the inf. [see also Visser sections 1253-1312, 1328-41]……