1．He studies by listening to tapes for a test．（就劃線部分提問）

                  he          for a test?

2．My sister had long hair in the past, but now she has short hair．（同義句轉(zhuǎn)換）

My sister                                    long hair．

3．Teachers should allow us to do homework with friends．（同義句轉(zhuǎn)換）

We should                      to do homework with friends．

4．It must be Carla's．（同義句轉(zhuǎn)換）

It must                   Carla．