The students will take morning exercise every day, _________ it rains.
Those were the graduate assistants ______ to do the research work in the lab.
It was dark in the cave so she ______ a match.
. ______ me most was that the young boy who had lost both arms in an accident could handle a pen with his feet.
It is quite common for a working man to make ______ for his old age by putting aside enough money to live on.
Classification is a useful ______ to the organization of knowledge in any field.