Some students have trouble _____grammar while others have difficulty______ new words.
Sara hopes to become a friend of _________ shares her interests.
He has some doubt ________ he will succeed in his research work.
_________ is known to all, the moon travels round the earth once every month.
Sorry, I am late. I ______ have turn off the alarm clock and gone back to sleep again.
___________ was most important to her, she told me, was her family.