“Thought” is a very common word, and can have many meanings. Used by itself, with no preposition, it usually means “to believe.” Used with “of” or “about,” it means to imagine in one’s mind, that is, to consider. With “about,” it can mean to plan. Briefly: Mental state: He thought a number of things. = He had a number of beliefs. Mental state / activity: He thought of a number of things. = A number of things came to his mind, he had a number of ideas, or he considered various things. Mental activity: He thought about a number of things / He was thinking about a number of things. He may even have been planning or daydreaming. If you make a mistake, you’ll probably still be understood in context. Note that the word “of” is usually reduced in speech to /əv/ or /v/. If no vowel follows, it is often reduced to /ə/ — this does not apply to your example, however.

think of 考虑,关心,想起,想象,有...的看法,记起 应该是记起的意思，可能是听力里面of的发音一笔带过，所以你没听清。