3.A may be preferable to B, but A suffers from the disadvantages that...

　　4.It is reasonable to maintain that ...but it would be foolish to claim that...

　　5.For all the disadvantages, it has its compensating advantages.

　　6.Like anything else, it has its faults.

　　7.A and B has several points in common.

　　8.A bears some resemblances to B.

　　9.However, the same is not applicable to B.

　　10. A and B differ in several ways.

　　11. Evidently, it has both negative and positive effects.

　　12. People used to think ..., but things are different now.

　　13. The same is true of B.

　　14. Wondering as A is ,it has its drawbacks.

　　15. It is true that A ... , but the chief faults are ...

　　二)原因

　　1.A number of factors are accountable for this situation.

　　A number of factors might contribute to the phenomenon.

　　2. The answer to this problem involves many factors.

　　3. The phenomenon mainly stems from the fact that...

　　4. The factors that contribute to this situation include...

　　5. The change in ...largely results from the fact that...

　　6. We may blame ...,but the real causes are...

　　7. Part of the explanations for it is that ...

　　One of the most common factors is that ...

　　Another contributing factor is ...

　　Perhaps the primary factor is that

　　But the fundamental cause is that ...

　　3.A may be preferable to B, but A suffers from the disadvantages that...

　　4.It is reasonable to maintain that ...but it would be foolish to claim that...

　　5.For all the disadvantages, it has its compensating advantages.

　　6.Like anything else, it has its faults.

　　7.A and B has several points in common.

　　8.A bears some resemblances to B.

　　9.However, the same is not applicable to B.

　　10. A and B differ in several ways.

　　11. Evidently, it has both negative and positive effects.

　　12. People used to think ..., but things are different now.

　　13. The same is true of B.

　　14. Wondering as A is ,it has its drawbacks.

　　15. It is true that A ... , but the chief faults are ...

　　二)原因

　　1.A number of factors are accountable for this situation.

　　A number of factors might contribute to the phenomenon.

　　2. The answer to this problem involves many factors.

　　3. The phenomenon mainly stems from the fact that...

　　4. The factors that contribute to this situation include...

　　5. The change in ...largely results from the fact that...

　　6. We may blame ...,but the real causes are...

　　7. Part of the explanations for it is that ...

　　One of the most common factors is that ...

　　Another contributing factor is ...

　　Perhaps the primary factor is that

　　But the fundamental cause is that ...