46.I'm not sure whether I can gain any profit from the inves

46.I'm not sure whether I can gain any profit from the investment,so I can't make a(n) ____ promise to help you.A.exact B.defined C.definite D.sure 47.If you want to _____ a pleasant visit,find out as much as possible about the manners and customs of your host country.A.assure B.ensure C.endure D.increase48.This is a very difficult operation.It is essential that you ________ for emergency.A.are to be prepared B.would preparedC.be prepared D.must be prepared49.A good way to ___ your vocabulary is to read a daily newspaper.A.enhance B.enlarge C.extend D.expand50.While writing a report,you have to write in a(n) _____ way.A.informal B.formal C.former D.foremost51.They are _______ enough to get into universities.A.formal B.fortunate C.familiar D.fierce 52.Of swimming and football he much preferred the ____.A.former B.fortune C.figure D.formal53.The little boy _____ his hiding place when he coughed.A.gave away B.gave up C.got away D.got in54.Tomorrow we’ll have the final exam,so I have to ____ the books again.A.go over B.go on C.go for D.go through55.It could be quite a few years before the product is _____ available.A.particularly B.generously C.generally D.individually