_U_ in quick.

40. _How many Substitutes has X?_
One.

41. _What is it?_
_Ks_ in exist.

42. _How many Substitutes has Y?_
One.

43. _What is it?_
_I_ in alien.

44. _How many Substitutes has Z?_
Three.

45. _What are they?_
_S_ in was; _c_ in suffice; and _x_ in xebec.

46. _How many Substitutes has Ch?_
Two.

47. _What are they?_
_Ti_ in question; and _t_ in nature.

48. _How many Substitutes has Sh?_
Six.

49. _What are they?_