31. What's the catch? 有什(shen)么意圖?

32. let the cat out of bag 泄漏秘密

33. sth. is touch and go 危險(xian)的(de)(de)情況;驚險(xian)的(de)(de);一(yi)觸(chu)即發的(de)(de)

34. beat a dead horse 白費勁

35. The sky's the limit. 沒有限制(zhi)

36. once in a blue moon 千(qian)載難(nan)逢;難(nan)得一次

37. Be prepared. 準備好

38. It's easier said than done. 說的(de)(de)比做的(de)(de)簡單(dan)

39. have second thoughts 考(kao)慮一下;猶豫

40. behind someone's back 在某(mou)人背(bei)后;背(bei)著某(mou)人