to have second thoughts about (something) (to start having doubts about [something] which you originally thought was good)

Eg 1:

A: I thought studying science at university was a good idea, but now I’m having second thoughts about it. I can’t understand the lectures at all.

B: You should talk to your professor about it. He will be able to help you.

Eg 2:

A: Helen had second thoughts about climbing Mt. Fuji when it started to rain heavily.

B: Had she started climbing?

A: No, she was just about to start.

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Can you make a sentence using “have second thoughts”?