The test not only helps make our _____ acquired knowledge permanent, but also enables us to find out what needs to take more time to improve.

After two years’ research, we now have a __________ better understanding of the disease. 

As is known to all language learners, the newly learnt words will soon be forgotten unless______ used in everyday communication.

Mr. Lin’s comments were very difficult to follow because they were ______related to the topic under discussion.

I cannot thank you ______ much of your kindness. I owe my success to you.