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.

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.increase
48.This is a very difficult operation.It is essential that you ________ for emergency.
A.are to be prepared B.would prepared
C.be prepared D.must be prepared
49.A good way to ___ your vocabulary is to read a daily newspaper.
A.enhance B.enlarge C.extend D.expand
50.While writing a report,you have to write in a(n) _____ way.
A.informal B.formal C.former D.foremost
51.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.formal
53.The little boy _____ his hiding place when he coughed.
A.gave away B.gave up C.got away D.got in
54.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 through
55.It could be quite a few years before the product is _____ available.
A.particularly B.generously C.generally D.individually