4亿年前，最早的水生动物——鱼类，是没有颚的，它们只能通过吸吮浮游生物或水底的泥沙来获取食物。当鱼类有了用于咀嚼的颚后，它们就可以追捕猎物，并用牙齿来制服猎物，从此，鱼类的生活大大地改变了。有颚的鱼又进化为两个主要分支：一类是像鲨鱼一样的软骨鱼类；另一类则有坚硬的骨头。由后一类又演化为今天丰富多样的有脊椎的鱼类，即硬骨鱼类，包括从梭鱼到海马约二万一千种。 如果以上论述为真，以下哪项陈述必然真( )

A．无颚的鱼类是有颚的鱼类的主要猎物

B．无颚的鱼类不以其他的鱼类为食物

C．硬骨鱼类不以吸吮浮游生物为食

D．无颚的鱼类没有软骨组织

单句改错。

( ) 1. We learnt from each other since we became friends.    _________

                     A      B                      C             D

(     ) 2. Danny said that he hadn't finished doing his lessons already.   _________

                        A                 B                   C                       D

( ) 3. She hopes you and I  to  come back  in two days.   _________

                                  A       B          C        D

(     ) 4. The teacher often asked us  don't speak  in class.   _________

                    A                      B              C            D

(     ) 5. Those poor children will be happy  only if we will help them.   _________

                                  A                 B           C              D

( ) 6. Your knowledge of Chinese are  tested when you play the game.   _________

                                     A              B       C                    D

( ) 7. This computer was  made  by Beijing  last year.   _________

                                    A      B      C                 D

(     ) 8. I'm sorry I forgot my English book at home? Can I bring it here tomorrow?   ________

                  A            B                                  C                  D

( ) 9. I was searching  the Internet  while my parents watched TV.   _________

                       A                    B           C                         D

( ) 10. We are made read English for  an hour every morning by our English teacher.   ________

                                   A                B   C                                D