In January , 2004, the United States successfully launched “Spirit”, a Mars Exploration Rover, _____ a new milestone in the history of mankind.
When ______ leave for Japan?” “When ______ leave for Japan is kept secret.”
“Is ______ you want to say?” asked the teacher.
He pointed to ______ looked like a tomb and said, “Ghost.”
After _______ had happened he could not continue to work there.
She was so angry and spoke so fast that none of us understood _______ he said meant.