Fill in the blank with a suitable connector (However, but, therefore, so)

I must say that you have done very well. ______, you should be aware that you still have a lot of thing to learn. 

Choose the best answer. 

The first part of the test was easy; the second, ________, took hours.

Choose the best answer. 

This is an expensive ________ very useful book.

Choose the best answer. 

He has done nothing to prepare for the final examination, ______ played.

Choose the best answer. 

___ hard he worked, he couldn’t earn enough money to support his family.

Fill in the blank with a suitable connector (however, but, therefore, so)   

This is the shortest way to the city center,  ______ it is not the only way.

Choose the best answer. 

________ long it takes, I will wait for you. 

Choose the best answer. 

Everyone ________ Tom is ready for the discussion.