Shelly had prepared carefully for her biology examination so that she could be sure of passing it on her first ______.

Scientists have found no ________of life on Mars so far,though great efforts have made on the research.

. The _____ look on his face suggested that it was he who had broken into the house.

When we heard the gun fire, we all stood still and shook with _______.

“I don't think it's my ________that the TV blew up. I just turned it on，that's all，”said the boy.