改错。下列各题划线部分中有一处是错的，请找出来并在横线上改正。

( ) 1. Hello! I'm Linda. I'm a Nurse.                                                 

              A              B               C

( ) 2. Is your unbrella blown?                                                          

                  A        B        C

( ) 3. That's isn't my cat.                                                                

               A      B    C

( ) 4. — What colour is this? — It's a red.                                        

                             A                     B  C

( ) 5. My book is green an orange.                                                    

                    A          B    C

煤的不均匀度越大，要采集到有代表性的样品越难。