Paper money was in_______use in China when Marco Polo visited the country in________thirteenth century.
If I drive in this city myself, I’ll probably get lost because I haven’t got ___ good sense of ___ direction.
_____ with her sister, Jenny pays special attention to her appearance. _____ she earns is spent on clothing.
Father made a promise ___ I passed the examination he would buy me an MP6 player.
There are so many viruses on the Internet. If ____ accidentally, the viruses may make your computer break down.
In front of our house _______ we used to swim.