2. It is （has been） estimated that the worlds population could reach 6 billion by the end of the century.

　　 3. It must be kept in mind that there is no secret of success but hard work.

　　 4. It can be seen from this that there is no difficulty in the world we can overcome.

　　 5. As is known man is the product of labor.

　　 6. It is a common saying that man who has a settled purpose will surely succeed.

　　 7. It is clear that the enemy has no desire for peace.

　　 8. It is hard to imagine how Edison managed to work twenty hours each day.

　　 9. Its hard to say whether the plan is practicable.

　　 10. There is no doubt that others will help you if you have any difficulties.

　　 11. It seems certain that they have made a series of experiments.

　　 12. It is said that bats have been using radar for millions of years.

　　 13. To tell the truth， many mistakes we made could have been avoided.

　　 14. As we know， it was not until recently that the problem was solved.

　　 15. It must be admitted that you havent done what you promised to do.

　　 16. In my opinion， this computer is different from that one you saw.

　　 17. It is certain that we have a long way to go.

　　 18. All this shows that nothing can prevent us from reaching our aims.

　　 19. As far as we know， it took him more than a year to write the book.

　　 20. It has been proved that every substance， no matter what it is， is made up of atoms.

　　 21. It has been decided that we are going to build a railway whose base must be completed within his year.

　　 22. It is obvious （evident） that the success of the innovation depends on our concerted efforts.

　　 23. To be frank， whether you like it or not， you have no other choice.

　　 24. It is natural that one may have trouble expressing complicated ideas in simple English.

　　 25. What is more important， the agreement they have negotiated is being carried out.

　　 26. We will be successful as long as we persevere.

　　 27. Frankly speaking， what you call the truth may not apply to things happening here.

　　 28. It is true that we must redouble our efforts； otherwise we cannot catch up with the developed countries.

　　 29. I take it for granted that they will support this idea.

　　 30. In a certain sense， a successful scientist is a person who is never satisfied with what he has achieved.

　　 31. The oceans do not so much divide the world as unite it.

　　 32. There is no denying the fact that the new management method has greatly increased the production.

　　 33. There is no denying the fact that the new management method has greatly increased the production.

　　 34. Upon hearing the unexpected news， he was so surprised that he couldnt utter a word.

　　 35. As the saying goes， nothing in the world is difficult for one who sets his mind to it.

　　 36. Our goal must be attained. Our goal can unquestionably be attained.

　　 37. Noting can prevent us from realizing the four modernizations.

　　 38. Now in China， more and more families can afford to buy high-grade goods， such as washing machines， TV sets， video orders.

　　 39. No matter how difficult English may be， you should do your best to learn it.

　　 40. It can be said that without knowledge of science and technology， it is impossible to build socialist modernizations.