11. teach fish to swim：班门弄斧
Teaching him how to speak English is teaching fish to swim.
12. early bird ：早起不睡懒觉的，勤奋的，吃苦耐劳的The early bird catches the worm; you have to get up early in the morning so you can have more time to read
13. cat and dog life：争吵不休的生活
Sam and his wife lead a cat and dog life together - they are always quarrelling with each other.
14. cold fish：态度冷淡的人，无情的人
We know nothing about the new student in our class; he is a bit of a cold fish.
15. scape goat：替罪羔羊
The criminal tries to find a scapegoat for the crime he was committed of.