英语完形填空,

题目

英语完形填空,
sixty percent of britain's food bill is spent on pet foot.48does anyone ever ask their petswhether they like what they are given to eat?Now a food producer has set 49 a food center in England,50 new kinds of catfood are tried out before they are put into production.thirty-six acts are given 51 very comfortable home at the center.they have longgrass to play in andwooden frames to climb on.Besides,52 have electric blankets and regular health checks.They even listen to the radio.In return 53all that,they work a four-day week.数字处填什么单词?一小时内!

答案

48.But
49.up
50.which
52.they
53.(供参考 ,只答出几道)