are you sure
你肯定吗；你确定要…
例：
Are you sure you can do well this year?
你肯定你可以在今年的考试中取得好成绩?
Are you sure he is your brother and not your boyfriend?
你确定他只是你的兄弟而不是你的男朋友么?
Are you sure it will work if any of our valuables like the archaized bookcase and the piano got damaged during moving?
你确定如果我们的贵重物品像仿古书柜和钢琴在搬运过程中损坏可以得到赔偿?
