_____ is certain is ______ the mystery of Stonehenge has never been fully explained.
People just wonder ________ that makes the housing price so high.
Jackie would like to buy an iphone 5 but _____ was available from that shop.
Before I left home, my mother taught me ________some simple dishes, such as noodles and garlic with vegetables.
In order to find the missing boy, the young couple all they can over the past twenty-four hours.
The young manager is well known for his problem-solving skills, ________ is important for a successful leader.