1．I don't think it a ________ (安全的) way to make a living．
答案：secure
2．Don't ________ (摩擦) your coat against the wet paint．
答案：rub
3．For food， he ate ________ (野生的) animals， fish and anything he could find in the forest．
答案：wild
4．You owe a ________ (某一) person a sum of money．
答案：certain
5．Your ________ (收入) must be declared on this form．
答案：income
