4._______ water to grow is well-known.
Human beings are different from animals _______ they can use language as a tool to communicate.
______ is often the case with elder people, my grandma talked about my new hairstyle for at least 50 minutes nonstop.
Come ______, everybody! Look at this _______, and you will find something terrific.
Up till now we _______ four units and this will be the second time that we _______ a test.
It was only after I came across that matter_______ how important it was to master a foreign language.