Complete the link sentence that leads onto the next paragraph which talks about 'pet mice': When choosing a pet, contact a reputable pet shop. Listen carefully to what the pet shop keeper tells you about the different pets and do not be afraid to ask questions. Make sure you will be able to properly look after the pet yourself before making the final decision. Dogs can be quite demanding, but one type of pet that doesn't require a lot of trouble ...

The 'topic sentence' introduces us to the subject of the paragraph and the 'link sentence' is a sentence that introduces the next paragraph: this ensures a smooth continuity in the text.