13. You had better keep your cell phone off when you go to bed.
你睡觉时最好把手机关了。
还能这样说：
I suggest turning your phone off when you sleep.
You should make your phone off while you have a sleep.
谚语：
Don't keep all your eggs in one basket.
勿孤注一掷。
14. I forgot to pay my phone yesterday.
我昨天忘了给手机交话费了。
还能这样说：
I omitted paying my phone bill yesterday.
I neglected to pay my phone yesterday.
谚语：
Elephants never forget.
象不忘事。
15. Your phone bill is due.
该交话费了。
还能这样说：
You have got a phone due to make.
You should hand over your phone fee.
应用解析：
due from 应收;
due to 由于、起因于，归功于;
become due 到期，满期
16. My cell phone is broken.
我的手机坏了。
还能这样说：
My cell phone doesn't work.
My mobile phone is out of order.
应用解析：
have a break 休息一会儿;
break from the past 和过去决裂;
break down 失败毁掉，拆除