thoughtful：沉思的，深思的；由thought(想法)+后缀-ful构成，类似的词还有helpful, careful, useful, harmful等。
举一反三
- You’d better not smoke. It is ______. A: helpful B: beautiful C: useful D: harmful
- ---It is a good way to study English with a group. ---Yes. I find it ________ to improve English. A: harmful B: helpful C: thankful D: careful
- — It’s a good way to study English with a group. —That’s true. I find it to improve our pronunciation. A: thankful B: harmful C: helpful D: careful
- t____________ a. 沉思的，深思的
- "Thanatopsis"isameditation(沉思,深思)on_______.