______ is surprising to us is that Tom, for ______ English was once boring, can speak English fluently as though he were a native speaker.
Make sure that the machine is kept where it is not ____ to children.
Mary is the only one of the students in our class who ____ to the Great Wall so far.
Two years ago, the 9-year-old girl set up ___ organization named Angel to help ____ homeless.
For miles around me there was nothing but a desert, without a single plant or tree ______.
More and more people choose to shop in a supermarket as it offers a great ____ of goods.