题目

Tomorrow was his girlfriend’s birthday and the young man was having a difficult time deciding on a present for her. She already had more clothes than she knew what to do with them, so he couldn’t get any kind of apparel. She never ate sweets, so candy was out of the question. What then? He had a very special reason for wanting to impress her with just the right gift; tomorrow he was going to make an offer of marriage to her. He finally decided on perfume(香水). All girls liked perfume. That raised another problem, however. What kind did she prefer? He couldn’t ask her because th求两条平行线l1:6x+8y=20和l2:3x+4y-15=0的距离.