大家好，请问 a 与 b 这两句话意思一样吗？我不太懂何时用动名词，何时用不定式。
A)He sat in his car watching to be sure I made it safely inside.
B)He sat in his car to watch to be sure I made it safely inside.
參考答案:A)He sat in his car watching to be sure I made it safely inside.
watching to be sure ...是伴随状语， 和谓语 sat 同时发生。
B)He sat in his car to watch to be sure I made it safely inside.
to watch to be sure I made it safely ... 是目的状语。表明he sat 的目的。
