She asked me which one I'd like, and I said I didn't mind.
她问我要哪一个,我说哪一个都没有关系。[动词时态一致,这是中国人学习英语最头痛的一个问题。]
Be careful! Don't throw your cigarette out of the window. If you do that, you may start a fire. Put it out in the ashtray.
当心!别把香烟丢到窗外。要是你那样做,会引起火灾的。把它熄灭在烟缸里。