There is ______ “f” and ______”u” in the word “four”.

What’s in your hand, Linda? —-A new book about Mo Yan. I _____ it ____ my friend.

_______ boys in my class can ski but _______ of them can do as well as Jim does.

The invention of spaceships makes ________ human beings to travel to the moon.

How long have you been studying at this school? — I have been studying here­­­­____.