To do something dangerous or risky.
危険なことやリスクのあることをする。
"You’re playing with fire if you invest without research."
"リサーチせずに投資すれば、あなたは火遊びをしていることになります。"
an idea or event that changes everything significantly
to express care or sympathy toward others
to become calmer after being angry or excited
to start behaving in an unusual or uncontrolled way
to have ambitious goals and aspirations
when something begins to decline in quality or popularity
