1. "The problem is that to improve balance, you've got to challenge balance, which is always risky," says Mary E. Tinetti of the Yale University School of Medicine,
    "问题是，要提高平衡能力，就得首先挑战平衡。这样做总是有风险。"耶鲁大学医学院的玛丽·E. 蒂内提说。

2. It´s a risky thing doing that.
    做那事要冒风险。